I have a couple of questions for those who went down this path.

I am interested in purchasing a generator for "emergency" situations.
CY: That's much different than a working generator for a farm or some
other situation.

I am
looking for something that is strong enough that could power the
heater,
sump pump, Fridge, etc (also, it does not need to do this all at
once). I
am also looking for something that has 240 out in addition to 120 so I
can
backfeed the house.
CY: Please consider a unit that runs on natural gas.

1.) What are the good brands of generators?
CY: Honda has the best reputation. Much truth the concept "you get
about what you pay for".

2.) Is there anything I should specifically look for in a generator
(warranty, serviceability, reliability, gas efficiency)?
CY: All of those. For occasional use, the repairs are less of an
issue. Gas efficiency should be about the same for em all. Worse for
some.

3.) Would you ever purchase one online? If so what site have you used
or
heard of other using with good success?
CY: I got a two cycle (mix gas and oil) generator from Ebay. Very
pleased with it. Only run it once, but the one time I did it was
quiet, and started on the third pull.