There are different ways to determine starting abilities of a character, but the standard one is to roll them as "4d6, drop 1", which means the player rolls 4 dice and drop the worst one, add them together to get a number. This is repeated 5 times, so the player has 6 scores to assign between the different abilities. This article on anydice shows what you could expect the player to get as abilities if they use this method. To sum up, their conclusion:
the average roll is rougly 16, 14, 13, 12, 10, 9
Most of the GM have their own way to handle this, and a common alternative for those who don't like random is a point-buy system where each character has a pool of points they can spend to improve each ability, usually it will cost more points to improve an already high ability, to discourage minmaxing.
With your method (sum of the abilities=80), players will probably have arrays of abilities like 18, 18, 18, 10, 8, 8, which is clearly better than what you can hope to get with most of the methods I have seen.
About their progression... Well, you are right, they only get one feat (it's not called a talent) every 3 levels and one ability increase every 4 levels, but they are supposed to also have all the features that come with their class level (like more HP, more skill points, a better bonus to hit opponents, more spells, more other class features...) The ability increase is very minor when you compare it to all the other bonus a character can get.
They also are indeed supposed to get better gear as they progress, but not as a gift as they level up. They are supposed to find this during their quests, or get it as rewards, or buy it... There is a table in the DM manual (that I can't legally link you here) where you can see approximately how much gear a PC of a given level is supposed to have.