I really appreciate all of the feedback on this issue! But, if found the problem yesterday. Turns out that the alarm switch for the rear door was disconnected and the wire was grounding out on the metal of the bus. Thus, causing the alarm to go off. As far as the interior lights, eggman called it! The need to be screwed in to the roof for them to be grounded. Again, I appreciate all the responses...
Well, until the next problem...!