It shouldn't be difficult. IIRC there was a recent talk on the subject if you can find it. I'm sure it would be helpful to have an extra set of hands available to hold the fan still whilst turning bolts. The problem you'll face is finding the correct replacement clutch. There were several horror stories about getting the wrong part from local autoparts stores.
2. The door will not lock. Seems like it will not engage and I cannot move the lock push pin on the door or engage it with my key. Any ideas? How hard is it to replace the mechanism?
That shouldn't be difficult either. It's likely that you won't even need to buy parts. Several others have talked about a rod inside the door becoming disconnected & fixed it with a zip tie.