Brake controller, Connecting harness, Two batteries?

I am new to this! - I have a 2009 TM2619 on order to be towed by a 2004 Sienna AWD van. I am having the hitch and transmission cooler installer on the van. Probably should have heavy duty turn signal relays installed as well. - My first question is what kind of brake controller would be recommended and how is the brake controller connected to the Sienna and/or installed in the Sienna. Would a heavy duty wire from the van to the TM battery as part of the connecting harness make sense?. - Would two batteries make sense? If so, is there room for two batteries? ----- SORRY ABOUT THE COMPOUND QUESTION. (I have a lot of questions floating though my mind in connection with this new venture!)