1) TM can be used for winter camping, no problem, but zero degrees is really going to be pushing it, IMHO. You are really going to have to make several modifications to seal air leaks and add insulation, and even then, I'm not sure how comfortable you will be. Condensation will be your enemy -- your windows will get ice on the inside for sure. We've camped in 15 degrees a few times, and was able to keep it pretty comfortable inside -- around 60 degrees. But the furnace was running fairly often, so if you are running on battery power, battery capacity will become of paramount importance. If it's windy, you'll have a very difficult time keeping it at "room temperature". All that being said, the shelter a TM provides is WAY better than a tent!
Also, as noted above, you're going to have to worry about plumbing freezing. You cannot leave the TM overnight, or for a comparable amount of time, unheated in that kind of weather. But if you have electrical hookups or a generator, some of these concerns become less of an issue. Mr. Geek's thread referenced above by T&C is an excellent reference -- he certainly has focused more on the problem than I have.
2) See this thread:
http://www.trailmanorowners.com/foru...ead.php?t=8100
In short, if you like to regularly go down 20 miles of washboarded dirt road at 20-30 mph, you're going to have problems.
If you want a true off-road outback trailer, check out Kimberley Karavan. Be prepared to shell out some serious cash, and import it from Australia as well.
Dave