oi think its any distance for normal phsycic abilitys and for shotting atatcks its as far as you can normaly move and shoot with a normal ranged weapon
as for the force staff thing, you can only do it if you can cast more the one power per turn
IE: you can cast two powers per turn, you cast a shooting power then charge, you can then use your force weapons because you still have a phsycic power left to cast that turn
Don't do it. If you find yourself thinking "Gee, I wish I had a Power Fist right about now" while playing IG, you did something wrong.