For organisational sake, I've moved to the One X+ forum, I hope that's ok? I'll have a pop at answering too.
I'll presume there will be a relatively stable 4.2 ROM very soon. The devs are normally pretty quick and unless there are massive differences between 4.1 & 4.2, I don't envisage you'll be waiting that long (although I'm not going to try to estimate).
I've found that aside from the camera, the benefits of Sense are minimal. It does have that element of polish about it, but it can feel clunky and it looks too cartoony IMO. If you do decide to root, experiment with different ROM, see what you prefer. The benefit of custom ROMs is that there's generally something there for everyone and with HTC devices, there's normally a good deal of choice so you're bound to find something you like.
Yep, you should be able to go back to stock, you can run an RUU which will reset your phone to HTC factory status. Alternatively, after you've flashed your custom recovery, take a nandroid backup and store it somewhere safe so you can restore that if you want to go back to stock.