Wiring trailer for dummy

I have a couple of question on how I should wire my trailer.

trailer- 2012 horton hauler hybrid. V nose 7X16 enclosed dual axel trailer.

#1 I want to run a 12 volt source in the actual trailer. I already have the battery and what not but I don't know how I can run it so that the truck will charge it while in tow? How am I supposed to tie it in with the curent 12V light already installed in the trailer. Would also like to run one more lightd in the trailer, standard 12V plug outlet, and possible roof fan.

#2 Want to add some clearance lights to the top of the trailer for better lighting in tight spaces. Do I just tie into the current lights and keep running a continous path to the power source?

#3 The only way I can use my current dome light in the trailer is by having the parking lights or headlights on in the truck. Anyway I wire it and use it without the truck lights being on? Or will it be better to have it work off of the 12V battery install?

As you can tell I have very little experince with electrical and how things work so any help or guidance will be awesome! I'm slowly trying to convert it to a toy hauler for a weekend warrior.