Do you have an aftermarket radio installed? If so it has a memory wire connected to the battery at al times and can cause a draw large enough to drain a battery in a week or so.
Did switching the wires on the headlamp switch repair the park lamp issue? They were origionaly hooked up so that when the headlamps were on the front park lamps were off, but when in the park lamp position all the park lamps were on.
