Psykers may focus fettered/standard/push.
Fettered uses full rating, but the dice are d5's.
Standard is standard.
Push may add up to 3 extra dice. Each '9' adds a roll on the PP as normal.

You may make 2 half action standard attacks in a round.
You may 'owe' actions into the next round where this makes sense.
E.G. Aim then autofire. You will then spend the next half action in the next round controlling recoil.

Unnatural Aim is an aim action. It does not stack with other aim actions but will stack with range mods.