I never had an EV so I can't help with all the questions... but I guess
adding an aux. battery is quite similar to do so on a vanagon...

is your EV an automatic or manual trans? is it a VR6 or a 5 cyl.? for such
price it should be in very very good condition, even mint... few years ago
I almost get a 2003 EV. 113K miles, 5 cyl., manual trans but I opted for a
1989 vanagon.

have fun with it and good luck...