QCan I use evolution points to pay for this follower's On Evolve ability?

ANo, you can't.

QCan I choose not to pay the cost of this follower's On Evolve ability?

AYes. In that case, you would simply not play the ability, meaning you would also not shuffle your deck.

QCan I choose 0 as the value of X when playing this follower's On Evolve ability?

AYes. In that case, you would search your deck for an Officer follower that costs 0 play points or less and put it onto your field. If you can't find one, or choose not to find one, you would simply shuffle your deck without putting a follower onto your field.

QIf I have 2 copies of this follower on my field, and an Officer follower is put onto my field, do I give it +2 attack?

AYes, you do.