The show lasts just a few minutes short of 2 hours. If Wishes is at 10, you will either get there or see Wishes from the boat, which is a great way to see it.
Yes, the last show of the night is around 9:15, so I'm guessing you'd have time to get there since it's not that far. I'd take the boat over to the CR and go from there. The busses are slow after HDDR lets out.
I don't know exactly how long it is but I know we hit the boats just right and got there in time for Wishes. DonaldT is right though, seeing them from the boat is great to.