I have aquired a used Miller 225 bobcat generator/welder. It has a 16
horse Onan engine. I think it run but have not had time to start it
yet.

Iit has a 8,000 watt generator. Is this decent sized? I was hoping to
use it to power the house or at least part of it in power outages.
(And of course to weld with it). I read on it that it could also do
tig and mig but cant see exactly how. I guess you woudl have to buy
more equipment.

Anyway, I have a 50 amp welder plug in my attached garage and also the
metal detached garage I have been working on. Can I make a plug and
plug one end to the generator and one end to the plug and "backfeed"
the panel in the case of a power outage? (Of course turning off the
main circuit breaker) My welding plug goes to a sub panel that feeds
fromt he main panel.

My metal building is about 70 feet away or maybe a little less. Is
this too far to keep the generator and feed the house throrugh that
welder plug?

Do these things weld well?