It does matter but only to a certain extent. IIRC paradigms are harder to drive then axioms. How much power you need depends on several things, how loud do you plan on listening, how effecient your speakers are, the impedance curve of your speakers, how big your room is etc etc. Also, keep in mind just because your receiver claims 100wpc doesen't mean it can deliver it without going into severe clipping. As far as the projector question goes, i'm pretty sure that any receiver with HDMI will work fine with a projector assuming the projector is an HDMI projector. How much do you plan on spending? What sorts of features do you want?