Here goes:
1. This is a pretty common symptom. Try replacing your PCV valve.
2. I have no idea, but I would suggest finding the cause instead of just removing the lamp in the idiot light.
3. I could be wrong, but this sounds really bad. I was going to say 'transfer clutch problems,' but now you say that you've been driving around in FWD and it's still happening. I would start saving for that new transmission.