I know you are going through a lot with this gremlin, but it is obvious to me that you are not driving it daily. Wouldn't it be easier at this point to remove the dash and get a better view of what was done under your dash?
I mean, a removed cruise control and two alarms so far, sound like a bunch of butchered electrical under that dash. Just make it more accessible and go to town repairing everything you find properly at this point.