First off, how in the world did your dealer rig and test run this boat without batteries?????
Now, getting past that, all you need is one switch for a single engine installation......or do you have twins? Here is the wiring diagram page from the Perko web site that shows all of the different hookups for single and twin engine/multiple battery installations. Just wire it like they have it and you will be just fine.
http://www.perko.com/cat_frames.html
Select the electrical product line and then battery selector switches. The diagram link is near the top.
As for the kind of batteries, your engine instruction manual has recommended battery ratings listed. Go with their suggestions as a minimum. There have been a number of threads recently on battery types and ratings....do a search. Four batteries is a bunch of weight, and take up a lot of room too......be sure that is what you want to do before proceeding. Most rigs only use two batteries. Hopefully some of the THT electrical sages will offer suggestions too!
Lastly, got to say again that you should not be doing this with a new boat.......the dealer should have done this all for you.