it requires another license if you are gonna use more than one ubb.. the easiest way would be to do the no-category-forum idea and point to it in your navigation - tho this approach doesn't allow you to have different "looks" beyond the header/footer, graphics, and colors... it's up to you depending on your needs, we bought another back before the price increase.
Being able to use the same memberlist is one of the features of ubb, just point your member paths to the same folder. I know a guy running 3 forums on the same member files... they all have to be on the same server tho...
