Starting my research on a new furnace.

[Chainsaw13]

I'm starting my research on a new furnace for my house. My furnace is 29 years old and still working ok, but I'm beginning to think its time to at least get the research out of the way before I'm under the gun. I have a small (700 sq ft), 2 bedroom home. The current furnace is a Trane, 95k BTU unit. I had a tech out today to fix my chimney cap that came off during the high winds we had last week. I figured since he was here, might as well get an idea of what a new unit would cost. A new Carrier, 95% unit installed would be around $3500, including a new humidifier. We would use my existing AC unit. He said with the higher efficiency, I would only need a 60k BTU furnace. I also got some prices on a new water heater since that's about the same age as the furnace. Might as well do it all at once.

Will a higher eff unit, but with less output be enough? The reading I've done so far suggests having a load test done to determine the right size.

Are two stage units worth the added expense? Will it work well in my application?

What manufacturers should I concentrate on researching? I've been reading some review sites already, but looking for real world experience.

Anything else I should know?