I am about to replace my old furnace and it seems that I will go with a G61MPV-36B-071. The offer includes a Honeywell 6000 and 10 yr Parts/5 yr Labor warranty. The contractor told me that the fan will have to run all the time on a lower setting.

I live in Vancouver Canada, mild climate and my house is ~2200 sq ft, 2 stories, finished basement. Basement is usually cooler.

My questions:
1. Is the G61MPV + Honeywell 6000 thermostat the right combination? Is this thermostat compatible wtih 2 stage furnace?
2. Is the G61MPV-36B-071 (66000 BTU) enough for my house? Another contractor suggested American Standard Freedom 95 Premium Input 90000BTU Output 72000 BTU. This one didn't provide the full model of the furnace and there is a big size difference comparing with the other one. What do you think would be the proper size? None of the contractors did an advanced load calculation.
3. Is it normal to run the fan continuously, as the contractor recommended?
4. Does Lennox warranty require an annual tune-up to keep the warranty valid? I searched their website and did not find this requirement.