Rick,
determine the room size and max. spl then go ahead and pick your speakers
if your room is quite large (I'm assuming it is since you're considering projection), i'm not quite sure if that Definitive set is for you. 4.5" mids can only go so loud. Keep in mind that the sub in that system is only 8". Except for all out horns system, there's no replacement for displacement.

as far as receivers go...if you like to keep things simple
almost any highend consumer ones will do
keep in mind that you don't need to buy the features you'll never need and buy one w/ honest power ratings

p.s emotiva has really good prices on decent amps...you really can't even DIY for the prices they offer