Bodywork Questions, also dumb mistakes

Just so you know, you're not the only dummy out there. I did it myself, and I've been working on cars since the 70's. I dodged the bullet on mine.
The fender with the least rust is the best choice. You want to pull, push , the metal in the opposite direction of how it was hit. You should look at any videos you can on how to do it. Eastwood has a bunch of videos. old fenders are good for practice.