^ You know it's funny because I saw the vibration of the trains in the videos, but I honestly didn't even notice. Both of my rides were on the blue train and I was assigned row 7 and then 9 (second from the back). You do feel a little bit of a shuffle, but the original Dragster had some shuffling as well, so I don't think you'll have anything to worry about. (Not sure how the other trains are though, so don't hold me to that!)
As for the lockers, I'd actually suggest renting one over at Magnum's entrance and then heading over to TT2. There should be less of a cluster of people just milling around not knowing how to operate the lockers, and retrieving things should also be way easier as I thought the TT2 locker area was a congested mess... and I went on a slow day!