I know that as a scout progresses he gets more attacks/round from his BAB. if using both attacks or all three is a full round action how can he gain the benefit from his skirmish which requires him to move at least 10 ft?
The best resource for this is KRyan's answer to his own question, "What are the best ways to move and full-attack in the same round?"
Add to his list the following:
I guess the point is to take 10 ft step (i.e. free action) to make a full attack later on. In that case, I know the following ways:
A final remark. I thought the point of the skirmish damage was to let a scout choose: either many arrows, each of which deal normal damage, or a single arrow, dealing lots, probably getting to do a similar amount of damage as in the full round. I am unaware whether getting the skirmish damage on all arrow hits makes the game unbalanced, but surely this is something to avoid, and it is something one should weigh based on the party he is in.
Scouts are kinda supposed to find a way, through clever character building, to get rid of this limitation. As Monte Cook explained in his Ivory Tower Game Design essay, D&D is a game where your character results depend on your system mastery - especially recognizing trap options (or, like Monte tells us, options that are not good in our game) and finding out combos.
So, while your first option would be "don't play a Scout, even if you combo him out it's not really strong"(1), your second option is "find ways to move at least 10ft before striking/shooting".
Some of these options are right there, hidden in plain sight in the bonus feat list of the Scout. The Manyshot feat allows you to dish out up to 4 attacks in a standard action and the Improved Manyshot one lets you apply your skirmish damage to all of them.
1) That depends a lot on your DM and on the power level and output damage of the rest of your group. If you're "not really strong" but nobody is or your DM manages to give you something else satisfying to do, that's fine.
This isn't fancy, but it gets the job done without straining magic item budget or depending on DM rulebending.
Very simply: take Quick Draw, Combat Reflexes, and Hold the Line. Humans can do this at level 3 without multiclassing, others at 6. Don't use a bow. Use a throwing weapon, preferably a throwing axe, and make "Returning" its first enhancement when you can afford it. Keep additional axes on yourself as well. Every round, position yourself at a point 30' feet away from your primary target and as far away from all other enemies as you can. Throw the axe for Skirmish damage. Most melee enemies will have to charge you to attack; when they do, AoO them for additional Skirmish damage. Then tumble away and repeat on the next turn. You will be an appealing target to ignorant enemies and nobody will be able to afford to ignore you for long, but the tactic will not be ideal against strong ranged enemies. Against spellcasters, ready your attack action each round to interrupt their casting. Keep your Spot and Hearing up and put "Seeking" as the second enhancement on your magic axe when you can afford it. Congratulations! You will be in charge of neutralizing spellcasters, and that will be increasingly important as you rise in levels.
After the three feats above, if you are married to being a two-weapon fighter, take Two-Weapon Fighting, Improved Two-Weapon Fighting, and Double Hit. I wouldn't recommend this, though, it has too little payout until you get Double Hit towards the end of your career; until then you will depend on non-Skirmish full attacks without Skirmish damage and they will be lame. It will be slightly less lame if you have a good flanking partner to set up flanks, but still only so-so. Alternative: multiclass with Ranger, and take the 2-weapon bonus feat path will free up feats for Swift Hunter and increase your BAB; take the Arcane Favored Enemy alternate feature and the results will be semi-good, but you will still have a long stretch with little payout for your investment.
However, instead of 2-Weapon fighting I would recommend Point Blank Shot, Deft Opportunist, and Weapon Finesse in that order. Again, you can multiclass with Ranger but take the archery path and substitute Swift Hunter for Point Blank Shot. Also, equip a light shield (people often forget rangers have shield proficiency). That shield will up your defense A WHOLE LOT and you can cheaply enhance it for additional alternate attack options as well. You will rarely be making full attacks so the loss of the hand to the shield will be no big deal for you.
As an alternative to all of the above, you could go full archer with a bow, forget the AoOs and melee combat entirely, and go with a combination of Point Blank, Rapid, and Many shot (again, you can multiclass with ranger for the archery path and take Swift Hunter instead of using your own feats for Rapid/Manyshot). Then you go with Dodge, Mobility, and Shot on the Run. You might be able to squeeze in one or two more feats as well. With these build(s), you never willingly go into melee and instead use Shot on the Run to emerge from and return to hiding every round wherever feasible. There is a lot to recommend that course, but with it you never, ever want to be in melee and will be weak where you can't find or make concealment/cover for hiding.
Pilot a Broom (or any mount technically, but totally best on broom)
This is a great way of building a character who, yes takes a thousand feats to be good, crosses a nice threshold from hey that's a neat workaround to "Look at my assault helicopter. Isn't he Pretty?". Steering with your Knees in a DC FIVE ride check, a 10 in combat, under duress. Key Defense points:
A flying shield (with arrow blocking) responds to a large amount of your immediate non-caster threats, is cheap, and works for all time, even on super awesome DM customized archers, but only once a round.
A godawful high Dex is key to hitting, not getting hit back, and your REFLEX save, so yeah, DO THAT.
Evasion, and Improved same, and something like a Ring of Invisibility (greater if you can get it) will protect you from rays and AoEs through mid levels.
An Airborne sort of flavor works very very well with a scout's military background, tons of fun to RP it all. I started this build as a Cohort cause it seemed cool but the story was heavily invested in the character with leadership. It quickly became not only my favorite, but a really useful tool; chasing other flying baddies, as a virtually silent reconnoiter build (no footfalls), the fastest non-monk in the party, and with Quiver of Elhalona (sp?), you can fit your entire character in one backpack (bows, brooms, arrows, spec. shots, wands (with 1 lvl rogue), etc). Cloak of the Bat is a ton of fun, and boots of spider climb for the same reason: sneak in by landing on ceiling and just walking in. Air walk is actually weaker than this because it takes an action to walk. Steering the broom is NOT a move action.
Best Race I've built this on: Silver Brow Human (Lvl 15). Free feather falls (otherwise that's another ring you SIMPLY MUST HAVE), and with two feats, you can convert you Precision damage dice to FIRE, which does work on Undead, Constructs, Plants, Oozes, and Elementals (except the obvious). Ghost also seems to have a ton of promise, but i haven't had time to every really look at it.
When your broom is taken away; The ceiling is too low, Anti magic, targeted dispelling/suppression, whatever. You are still a decent Arrow Machine Gun from the ground, you just need to do a bunch of the regular work-arounds to earn Skirmish.