What batteries for stereo, and install help?

I am doing my stereo this weekend and I need to know what batteries to hook up and how. My R20 came with an interstate deep cycle battery, and I have a switch already installed by no second battery.

My stereo set up is an Alpine PDX5 running 6 interior wetsound 6.5s, and a 12 inch JLw3. I have an Alpine PDX4.150 running two Rev10s on the tower.

So what battery do I get for the stereo and how do I hook it up with the switch? On my last boat I had all the accessories, alternator, stereo, etc hooked up to my switch, and changed it from battery 1 or 2 depending on how long I was running the stereo, then when the boat was running I had it switched to ALL position. I'm reading people running one battery for starting, and 2 bank batteries for stereo, but I don't know how to set that up.

Thanks for the help!