welcome to iRV2.
Although your coach is older , many of the appliance manufacturers could still be in business , so collect the names and model numbers and look for info on web sites. Many users manuals available as free downloads.
Other questions can be answered by checking out the " Files " drop box , just to the right of the " User CP " in the blue bar across the page under the " Google search " box and your welcome message.
For basic info on RV 12 volt systems perhaps this site will help.
The 12volt Side of Life (Part 1)