before you spend all your time taking stuff apart i had these probs with my car when it had been stood
firstly the heater, check fuses of course, but if you open the bonnet take the wipers off, then the scuttle panel, then the wiper mech (looks and sounds worse than it is) u will see the blower on the passenger side of the car, see if you can spin it, i gave mine some heave hoe as it was seized sprayed some wd40 on it now its fine,
with the fuel cap, does the button make a click when u push it in? if so give it a few pushs contacts could be damp, still dont work after that take back seats out and on filler cap side there a a connector that goes to it make sure it tight or even just run 12v to it and c if it fires,
window not workin check fuses and check switchs for clicks again, last resort give the motor a tap with a hammer, if sill no go get a tester on the motor and c if you have 12v goin to it.
hope this helps may point you in the right direction
TAKE REVENGE!!!, Sh*t On A Pigeon