I was so nervous moving #2 to a "big boy bed" and it ended up being for no reason at all. If she sleeps 10 - 12 hours already, and is dry all night, I don't think you have anything to worry about there. And it will actually make tucking in much easier. No lifting at all! At her age she's ready for the independence. I would just stay up in the vicinity until I knew she was asleep, then you don't have to worry about trips up and down stairs, since clearly once she's out, she's out for the night.
As for potty training, sounds like she's ready!