I'll try to clarify for ya.
There are spells/abilities and then there are talents. We hunters are given abilities, these you buy from hunter trainers, all they cost is the silver/gold you have to spend to gain the ability.
On your primary toolbar where you view your quest, your character status, etc. there is a link to talents. Talents are for the most part independent of your abilities (you can earn abilities by using your talent points in certain marksmanship talents, like Aimed Shot). Every time you gain a level you gain a talent point, they are free and can only be used on your talent tree ( the 3 areas you already mentioned) it does not cost anything to use them and when you buy an ability from a trainer you do not lose any talent points either.
Hopefully that explains the system, with few exceptions they are independent of each other, and talents tend to usually boost or enhance your abilities that you buy at the trainer.