the price of the 15 SEER was $600 less or so. We plan to be in the house for a good while 10-15 years ++??

So, I thought it may be worth to spend the extra money to get a the 18 SEER. This has a 2 stage compressor...more efficient.

Where will furnace be located?

For Virginia, i would prefer the XV95 95% eff furnace over the 80% XV80.

Recheck coil model numer and ask for matching AHRI number.

New lineset?

Filter cabinet?

Don't kid yourself, the two stage compressor is more about comfort than efficiency. You would want dehumidify on demand set up for AC cooling. Discuss with dealer.

Nothing special about the pricing.

IMO

If you are going to be in the house for 10+ years then why not get a 95%+ AFUE furnace?

Was a load calculation done? A 3 ton condenser seems for the first floor.

Make sure you are getting a Trane coil.

The number on the COIL is very similar to the Trane Cased R410A COIL.

They are putting in the 4 in filter cabinet.

What is Trane evap coil model number? A third party coil is not acceptable. You don't want it.

What size furnace?

TD