There shouldn't be any problem with getting MongoDB to run on a UV.
1) The UV uses Xenon processors, so this shouldn't be a problem, provided the addressed area of memory doesn't change from under the application. That is, when trying to access area A of memory, and the data has been moved to area B by another process, MongoDB will not like that.
2) Yes. You can use Debian without an issue - I have done this many times in production.
The UV is a fairly exotic machine to be running MongoDB on, so my reply is an educated guess having briefly used a UV before for testing.