bump, just to help you out there...

There is no way to give you a price per sq ft because lots and houses range so much in needs and in materials. For example, you may have a sloped lot with heavy vegetation which may require extra excavation and special engineering with more steel or concrete. You may choose special flooring, expensive lighting, high end windows and doors, high end appliances, a complex HVAC system, etc., etc. that will make the price appreciably different than those who make other choices. We did our own wiring, but had electrician friends tell us that 'builder's grade' wiring would have been $10-15K for our house, but the way we did it, with the details the way we wanted, it would've been double that. Also, things like the complexity of the framing (jogs, dormers, angles, etc.) will make a difference. Our window package was $7000, and others here have had ones for $40,000. TOO many variables. If you have a plan, you should be able to take it to a local lumber yard or builder's supply and have them do a 'take off' to give you ball park figures on the basic construction package. There are really no shortcuts to guessing how much a build may cost you.

On fireplaces, if you mean 'prefab' vs built in place, I'd go for prefab. Likely more efficient and less expensive...Just my opinion, though, based on my limited experience.

Best wishes.