In-ceiling Speakers whole house system going in

Looking for some advice . . . again. Having home audio system installed but concerned over a large open space: the kitchen, dining room, living room - talking about 35ft[w] x 25ft[l] (split evenly on width between "living room" area and kitchen/dining area). This will be for music and there will be a speaker zone controller unit.

Its a older home so have 8ft ceilings and hardwood floors throughout.

WAF is in play so anything that isn't flush mounted is out - so no Gallos.

1)How many speakers in a space that big? 6, 8 or . . .

2)Roof line is pitched so should I look at speakers that are "boxed" versus infinite baffle-types.

3)I was looking at NHT iC2, Paradigm CS-60R, Home Theater Direct HD-R80 and Energy EAS-6C/RC-6C {BUT always open to suggestion on speakers: KEF, Sonance, etc...}

4)I really don't want to spend $500/speaker - I will if I "have to."

Lastly, if I get desperate I guess there is always Crutchfield.

Thanks ahead of time.