Originally Posted by Stretch

If I were you I would tackle those jobs in the order you've written them.

#1 needs to be fixed ASAP - you don't want an electrical fire. You don't really need to do the upgrade - you just need to make it safe.
#2 needs to be fixed soon so you don't end up with a flat battery.
#3 can be fixed later on - whilst you are figuring out what's gone wrong be sure to replace the valve cover gasket as well - these often leak as well.