why dont you just put a 5th gen glass sunroof on your 4th gen. with very little modification to the railling it will fit perfectly... then with the glass sunroof you wont have to worry about rust

as for the orange out of the taillights... its easy. bake 350 in your oven for 3 minutes. pull it apart and take the orange piece out. then you will need some clear plastic bubble sheet or something like that (they use it for light fixtures and stuff) and cut out a piece to replace where the orange was... then bake for another 3 minutes and put back together, let the glue dry back up, check for cracks and if any are found fill in with apoxy