1. If they are both up, refresh once for UVLS, it will also be LMG buffed, and that's that.
2. B is the answer. Depending on amount of ticks I estimate to have happened, I may try to catch the end of the LMG proc. You haven't clarified if this is with 2 piece or without by the way.
3. Again, this changes with 2 piece. At the moment, I'm refreshing, treating it like a lust. I don't have the 2 piece though.viewtopic.php?f=8&t=3582&start=60
Check out that thread for a great add on for tracking relative dot power and when you overwrite.