Yes, Deadly Aim is worth it.
The math in Pathfinder tends to work out such that people who want to attack tend to have a bit too much attack bonus—and need ways to turn their extra attack bonus into damage. Many, many features revolve around doing that.
For example, most archers also use Rapid Shot, −2 attack penalty for an extra attack.
But ultimately, archery is a combat style with a lot of extra attacks, but tends to struggle with actually getting significant damage on those attacks. Deadly Aim adds damage to every one of those attacks, which is what makes it worth it. And archers are often full-BAB, and should go all-in on Dexterity. They should have plenty of attack bonus to spare.
Trying to switch weapons, however, is not.
What isn’t worth it is the greatsword, or the 18 Strength. If you absolutely must have a switch weapon, make it something you can finesse, and then take Weapon Finesse—except don’t do that, because it forces you to split your feats and your wealth and you just end up sucking at both melee and range.
There is basically zero reason for an archer to switch to melee anyway: unlike a melee character who can be faced with an opponent you can’t reach, a ranged character can always attack. You do provoke attacks of opportunity if you are too close to an enemy when doing it, but in my experience, it is a very rare case where you cannot simply take a 5-foot step away from enemies, and then fire away. Even when you can’t, switching weapons would take your entire turn—if you are going to waste your entire turn anyway, you might as well just reposition so you aren’t in harm’s way and can utilize your feats and class features optimally. Expending very scarce, very precious resources (ability scores, feats, thousands of gold, actions in combat) for such rare scenarios is not a winning strategy.
Also, getting Strength just for the damage bonus on ranged attacks isn’t really worthwhile. You’ll probably have a certain amount of Strength just to carry your gear, and I’m not saying you should ignore the +1 or +2 you get that way. What I’m saying is that an 18 costs far too much for what is, at best, a fourth-rate concern (after Dexterity, Constitution, and Wisdom), and magical items to improve Strength should be very low on your list of priorities (to the point that you’ll probably never bother to get them).
Which leads me to a broader, more important point:
You cannot afford so many ability scores
Pathfinder absolutely does not support characters who care about more than two or three ability scores. You need Dexterity to hit with your archery and to qualify for archery feats, and you need Constitution to not die. Some Wisdom would certainly be good, too, considering the existence of ranger spellcasting; you might be able to manage a bit there (certainly at least the 14 minimum you need to be able to cast all the ranger spells, but hopefully a bit better than that by the time you get high enough level to worry about them).
But adding Strength to this is only going to hurt you. You will pay far, far, far too much trying to keep everything up to relevant values, and you will suffer immensely for it. Note that the game’s math assumes you do have the latest and greatest enhancement bonus to your attacking score rather soon after it becomes affordable, and that the game chargers you 50% extra to get an enhancement bonus to a second physical score—you will, by definition, be unable to keep both Strength and Dexterity high enough to actually hit things.1 Pathfinder very simply does not support the kind of character you want to make.
But what about all of these problems that might happen?
I took quick draw so switching weapons is something of a non issue. I played under this DM before she will target weapons and weapons are dropped on a one. What then if my bow gets destroyed? What if I have to fight underwater? As I use arrows in her game some will be destroyed or lost. Doesn't switching to melee at times conserves arrows? I cant always run back to town and crafting arrows takes time
I know the DM and [the efficient quiver] is the type of item she rarely if at all gives out or lets players buy or make.
All of these concerns are real, but many of them are not actually a part of Pathfinder, but rather things that your GM has house ruled. I would, generally, recommend strongly against a GM doing any of those things, both the house rules and the pedantic implementation of the official rules. But nonetheless, if that’s the game you’re playing, you have to have answers to them.
That doesn’t change the fact that the greatsword is a poor answer to them. Quick Draw only covers drawing a weapon, not sheathing the previous one, so you either waste an entire turn—and therefore might as well have just repositioned—or else have to drop your first weapon, which sounds like an excellent way to lose it. Losing a magic weapon can cripple a mid-to-high-level character; even as early as 4th or 5th level the game just punishes you massively for not having one. (Actually, it can do that as early as 1st, even though it’s generally impossible to have a magic weapon at 1st.) And greatswords still suck underwater, and eventually you really want some form of freedom of movement anyway.
But you can get around some of the issues if you’re clever. The name of the game is to protect your investments, rather than trying to diversify.2 That is, don’t try to use a Strength-based greatsword and Dexterity-based longbow, use one weapon, and one ability score, to do both things. And to do that, you should
Seriously consider throwing weapons
If you really want to excel both in melee and at range, don’t use two weapons, use a weapon you can throw. Use Weapon Finesse—or better, save a feat by using effortless lace—to make the weapon use Dexterity for attacks even while in melee, so you don’t need Strength. Use a blinkback belt, and ensure you always get your weapon back—whether you threw it, or dropped it because of the absolutely atrocious houserule about dropping weapons on a 1. Unlimited ammo, because you just keep on throwing the same weapon over and over.
If you really want, you can have a throwing sword. You can’t use a greatsword since blinkback belt is limited to one-handed weapons, but you could have a longsword.
And you build that character mostly like an archer, probably. You pay an extra feat for Quick Draw, and your range is limited (you might want a second feat for Far Shot, though it doesn’t help as much as it should), but it gives you a fallback option for when you absolutely cannot attack at range. Hopefully some of your feats, and all of your weapon bonuses, apply to those melee attacks. Deadly Aim is still worth it—and Power Attack isn’t, because most of the time you’ll prefer ranged attacks, the melee option is just for emergencies, and for low levels before you can afford the blinkback belt.
(And if you really cannot find basic gear like this in your campaign world, someone in the party should be crafting. Crafting is a massive advantage even in a typical Pathfinder game; in a game like this where you can’t just find things, it becomes absolutely crucial. That’s not even metagaming, if you live in a world that relies on magic but it’s hard to find, every serious adventuring group would make sure to have someone who could provide it.)
About the game overall, or, seriously consider just being a sorcerer
But really, it has to be said: your GM is applying a ton of house rules that very, very negatively impact mundane, martial characters—already the weakest characters in Pathfinder. Dropping things on a natural-1, the inability to find or even make relevant magical items, these are major departures from how Pathfinder works. For that matter, going after weapons and meticulously tracking ammunition are things most GMs just don’t do—because, as I said, Pathfinder martial characters have enough difficulties without actively trying to screw them over.
I don’t know all the details of your game. I don’t know if there are also changes to magical characters, that even things out again, and I don’t know if there are adjustments to challenges and monsters to make them workable in this setting. Hopefully there are. But from what I’m seeing, these rules make the game so antagonistic that you are all-but-forced to choose absolutely self-sufficient characters. Which means, I guess, everyone should play a sorcerer always. Nothing to steal or break, no absolutely mandatory equipment to just not have, no god who can arbitrarily decide not to give you spells that morning. Which is precisely why these sorts of house rules are so heavily recommended against: the natural response to them is to just avoid the classes that are getting shafted, and gravitate towards the classes that can avoid them. That reduces the diversity and variety in your game, and that’s generally seen as a bad thing for the game. Most GMs try, instead, to bolster martial characters, to make up for their systemic shortcomings, and instead try to reign in the spellcasters, who are far too powerful to begin with. By doing the opposite (again, if that’s what is happening—I don’t know what other house rules are in play), you end up instead just making it that much more beneficial to just stick with the overpowered classes.
Note that I strongly recommend ignoring this rule entirely; it’s absolutely awful. Ultimately, though, even without the 50% surcharge, you still can’t keep both scores up, at least not without doing something disastrous like having suicidally-low Constitution or ditching what is actually your strongest class feature, the spellcasting that needs Wisdom.
I am not a financial advisor and really know next to nothing about finance, but it is my vague impression that this would be terrible financial advice.
