Yes, he does build awesome boats.

Well, I would bet the stock motor and prop will give a good "scale" speed to the boat. It is much too easy to exceed scale speeds and make a nice scale boat look foolish, imho.

But anyway, just about any simple marine esc should control that 550 motor easily. I would go for an Mtroniks Viper Marine esc from Hobby People:

http://www.hobbypeople.net/gallery/159230.asp

And you will only need one servo, for steering. The electronic esc negates the need for a second servo. The Viper esc can handle 10 cells, ( 12 volts), so you could really make that motor cry out for mercy if you wanted to. I would just run it on a 6 or 7 cell battery pack. You will probably be very pleased with it at that level of performance.