How closely do the rules for shooting apply to psychic powers? For instance, can you use a psychic power with a description like "this power functions as a weapon with the following profile" on one unit and then charge a different unit in assault? How about a squad of 8 possessed Tzeench chaos marines all with Doombolt -- do they have to all fire at the same unit? If the Aspiring Champion has Bolt of Change instead, can he fire at a different unit? What about powers that don't count as a weapon, which instead say "Choose a unit within 6" and half of them turn into goats" or something?