first off engine running issues. If your not too sure then take it to someone who deals with them. It will save a lot of guesswork and internet advice.

Heated screen cables are located by the tops of the wing rails and have 2 cables per side with spade terminals which are heatshrunk.

Heater motor just replace complete unit 2 nuts one plug and a cover its out.

Every man and his dog will give advice on your engine probs and you will be chasing issues which are not a problem and possibly causing more harm than good. Without having the car in front of you its all guesswork.

Regards
Paul