NEED HELP!!!! ... from the PROS and homeowners.

I plan to upgrade the HVAC system in my home.

The contractor�s original quote was:

Carrier "Infinity" Model 25HNA936A003 air cooled heat pump condenser rated at 19 SEER. Two (2) stage air cooled condenser matched with the Carrier "Infinity" Model FE-4-ANF-004 variable speed air handler and the Carrier "Infinity" Model SYSTXCCU1D01 controller for two (2) stage heating and cooling and dehumidification

The final quote was:

Carrier "Performance" Model 25HPA636: 2 Stage / 3 Ton � 1.5 Ton / 36,000 Btu � 18,000 Btu air cooled heat pump condenser rated at 16.5 SEER, 208/230 volts, 1 phase, 35 amps, R-410A refrigerant; Carrier "Infinity" Model FE4-BNF-003: 2.5 to 4 Ton / 1000 to 1600 CFM variable-speed indoor air handler; Carrier Model KFECH0320N20: 20 KW electric heater package; Carrier "Infinity" Model SYSTXCCU1D01-B: 7 day digital programmable thermostat Controller with dehumidification and fan cycle modes

For both systems, the price quote was:

Base price (Equipment & installed): $11,400

After federal tax credit: $9,900

The explanation provided for the change in models was:

The Carrier Infinity HNA936 Series could get to 19 SEER. With the changes in the HNA936 Series engineering, the HNA936, matched with the FE Infinity FE-3-003 air handler will get a 17.2 SEER and will now cost $900 more. Carrier no longer builds the FE4-004 air handler and to get an 18 SEER (the highest now available in the Carrier line) we would have to go to the FE4-005 or 6 air handler which will not fit in the closet space. The Carrier Performance match up at 16.5 gives us the best features (All of the Infinity features) at the better price and a slightly lower SEER (16.5 instead of 17.2).

1) What is the difference between the Carrier Performance vs. Infinity model?

2) What does the change in SEER value mean?

3) Is the cost reasonable for both models?

4) Which package is best?