You're making things overly complicated.
Houses don't rent by the sq foot! It's more a matter of how many bedrooms a house has. Unless of course you're renting some 10000 sq ft mansion, or something. Also, don't buy 4 bdrms to rent out, you'll regret it. Stick with 3bd-2ba-2car. If you *have* a 4 bdrm, advertise it as a 3 bdrm, unless you're looking for sec. 8 HUD money.