Psychic powers that are attacks perform what is called a "psychic attack" it counts towards the 1 attack per turn limit (including preventing the use of dual wielding).

Because it is an "attack," can it benefit from the Aim action, which provides a +10 bonus to the next attack made that turn.

Seems legit.

Yes, if you take the time to Aim your fireball, or the swing of your psychic projected sword, I don't see why it would not apply.

Given that evade works on resisting psychic attacks it looks to me like it is classified as a regular attack, which means aim should work fine with it.

Remember though, its always evaded by WP. Sure PCs are going to buy up evade anyway, but I do think the people that seriously go in for the crazy high AG will find out pretty hard that psykers are gonna hurt. Especially now with how lowering the PL of a psychic power increases its accuracy.

A PR 4 psyker could cast assail at PL 1, get +30 on the check, and aim twice, +20, as well as assail being a base +10. WP +60 test, vs. your WP + Evasion. Have fun.