If you plan on painting it yourself, you will need some warm weather or the paint will run. As far as the metal work, you will probably find that the rusty areas will be worse than they may appear now. I don't like the idea of fixing rust with fiberglass/bondo, because you can't. You mentioned that you can weld. Cut out the rust and fix it right. I guarantee you will be happy that you did when you are done.
