Brettski, I'd go as big as you can afford. At least 4 ton unit. Much depends on how well the building is insulated as well as exposure, air infiltration, etc. The difference in cost between a 3 and 4 ton unit use to be only $300. As far as the well goes, I strongly suggest you consider 2 well tanks in parallel. Your well pump will cycle less often. Most all the wear and tear on the well pump is in the start up. Well pumps will typically draw three to four times the amps at start up. Put an amp meter on the power lines going to the pump, and you'll see. Any well installer will tell you that it's better to run the pump continuously with longer fill times, than constant cycling every 5 minutes. This cycling will eventually burn up the pump. The only way to accomplish that is to add pressure tanks.
