A man with a plan and a great opening post.
I reckon, keep just the tv and don't bother with a screen for now.
Spend the budget on a pair of really great front speakers and a powerful two channel amp.
I've heard how loud and clear the Klipsch RF 7 II went, these will fill you room, house and street.
Build the rest over time and never pay RRP.
Think about adding a home theatre pc or nas to take advantage of internet tv/films which really is the future.