It's a small house, but we have 3 different bedrooms and the living area that would need cooling. We would need 2 split ACs then? That would drive up the price? I did have a split AC unit earlier, and liked it, but the layout of the house allowed for 2 units to cool 1000 sq ft. Not sure how this would work here.
I suppose a few smaller split systems might work but at that point installation and maintenance costs are going to get ridiculous quit quickly. Unless your central heat intake is in the main living space and could circulate the cool air from there throughout the house (not very efficient anyways) I suppose it really wouldn't work to keep that many rooms cool. Just trying to throw ideas out there.
I think 3 tons is a little big for your size house and climate.
Actually, that totally and completely depends on the house. If there's a lot of South facing glass, that house will get a lot more sun and heat up a lot more. The air conditioner won't be able to keep up. Other things play a role as well, such as how much insulation you have and how many windows and glass doors there are. Are your windows shaded, etc.
Any contractor worth his salt will always do a heating and cooling load. If they don't, kick em out and find someone who will.