Hi, First of all, I am not an HVAC pro so my comments are only general ones.
1. There is no "best". It is sort of like asking which American car is "best". It depends. Some people swear by different brands vs. other ones. What probably matters more than any particular brand is how your hvac pro. feels about it, installs it and stands behind it. 2. heat pump... I don't know. 3. There is not absolute rule that correlates the square footage vs. the tonnage of the unit. Again, it depends. There are many factors involved and anyone that tells you, "oh this size house definately needs this size unit" without doing an on-site inspection, you should shy away from. Some of the factors are, the layout of the house, how tight it is, how well insulated, how much glass and what type, etc. etc. etc.. You are best off trying to get some word of mouth recommendations for air cond. contractors. Then I would get three estimates. If one is wildly different than the others ask him why. If his reasons sound good then maybe ask the others why this one is so different etc. 4. 14 vs. 12 seer, again it depends. This is a whole discussion in itself. If you want to see many thoughts on this then go to: http://www.todayshomeowner.com/forums/heatingcooling.html