As far as the electrical problem goes I would have a really, really good look at the battery terminals and wires coming off of the batteries. I've seen wires that look good but when you strip the insulation back there is nothing but corrosion.
As stated above I would find a really good shop that specializes in electrical problems. Big difference between a general mechanical shop and a shop that specializes in electrical problems.
Good luck!
(On edit) Looks like Ben had the same idea I did! Great minds think alike. :)