I think the getting off the water quick is a good idea, esp with a 3ch on 2 floats, it's just not going to high speed taxi very well, so just get off as quick as possible once you have enough speed to not stall.

Control reversal is a pain, It is probably the single hardest thing to learn in RC flying. A couple of pointers to try that helped me when I was learning solo with a seaplane:

Try not to fly directly towards you, this is when the tendancy to do the wrong thing is the most strong. If you fly in a big oval with you on the long edge, then the plane will always be flying away from you as you initiate a turn. Remember what stick movement got you into the turn, and use the oposite direction to get back out if needed. Since it's a 3ch with dihedral, it should self correct somewhat.

When you are flying towards yourself, or at any time when learning, avoid big control inputs, give a small input, see if it starts turning the way you like, if not, reverse the control. This is not a normal feeling, but it saved me a lot when I was first learning. I learned on alerons, rudder will be slower to respond, so may not work as well. The main thing that kills novice pilots, is they try to get out of a turn with the wrong control, which makes the turn into a dive, and they crash with the stick buried the wrong way. As you learn, you will become much more aware of your plane responding to your inputs.

Fly in dead calm air. That way you won't be seeing gusts as controll inputs, and you won't need as many tiny corrections that you might get wrong. I fly on a lake around a lot of trees and hills, this chops the wind into lots of little bumps, up drafts and down drafts, which makes flying tricky, esp with a slow trainer. I am a much better pilot in dead air, and it makes seeing your plane respond to your inputs much easier. At least around here, Morning and evening are the best times to fly.

Best of luck, and don't stop when you crash, everyone flying RC crashes once in a while, the only ones who never crash have stopped flying.