Hi Mike and welcome to the forum
The Alpine is a scale model so just get some geared down MFA motors as they don't actually need that much power. They sail very slowly but need lots of ballast to get them down to the water line. I used 2 - 12V lead acid batteries in mine and the it needed some extra lead too. As for ESC I would recommend Action electronics as they are easy to install and are probably the best on the market for what you require.
Good luck with your build and why not start a build log? Get loads of pictures up too
Mark