Flying vehicles is a bad idea. People would cheat the Log Challenge or treehouse by flying to the top or flying someone else to the top. Even if you made it so you couldnt enter the vicinity of them, people would fly over them, jump off, and catch on with their hook. Furthermore, you could get to places you shouldn't like the exterior of the shop interior.
Personally, I would like the stats system to return, however it shouldn't be able to be leveled up, and it shouldn't affect players too much. Players should choose stats when they start and be stuck with them.