I would not recommend hand launching it at all, you will be sorry.
I put a thunder tiger .07 on mine. I fly it off of the ice and it fly's very nice. With the .07 at full power(when not fully broken in) there is only enough power to do a stall. Nice slow flyer.
I put in a 600 ma battery and I use small servos. I have not flown it off of water yet. You could make a cradle that you could use as landing gear, and rest the plane on it to take off from a cement runway. As you lift of the landing gear would stay on the ground.

Have fun