overheating eh? a common cause of sputtering to a halt is a bad condenser, try wiring in an external one. If the condenser's bad it'll need to cool off before running again, and there'll be no spark when it dies so check for that\
the other common cause is poor fuel flow and the bike draining the carb bowl faster than it's filling. that's easy to check so give it a look-see
as for the headlight and horns, check that you've got power coming out of the stator on the lighting wire with everything else disconnected. it's probably either the coil's shot or more likely the wire's grounding out somewhere. if you got a multimeter or continuity tester just isolate the segments of wire to track down the faulty ground.