[villagetinker]

I am not sure anyone here can tell you the size home you should buy. there are way too many things to consider. IMHO, call one of the Village Realtors, we used Priscilla Hart, she was very helpful. You really need to see the houses, so that you get an idea of the size, layout, etc.
If you are lucky enough to buy a lot and build, then you can get various upgrades built in to your house. If you are buying "off the rack", then IMHO, move in get a fell for the house and the area, and then and only then start the upgrades. The exception to this is garage floor painting which is better done before anything is placed into the garage, and carpet upgrades for the same reason.
You can easily put several thousand to several tens of thousands of dollars into upgrades, that later you look back at and regret. We did almost nothing fro several months, then small projects. The major upgrade, a new birdcage and major landscaping was almost 2 years after we moved in and were sure what we wanted.
Hope this helps.