Paint and Body Does my floorpan need replacing?

It's hard to tell from your first pic, but that first pic showing the crack through the floor should be fixable. First question, can you weld? If so, I would drill the beginning and end of the crack, weld up the floor pan, clean it up, paint it, and call it good. The seat brace is also fixable. What ripped out of the seat brace was the stud and reinforcement behind the sheet metal. Should be able to get the right sized weldable stud (or bolt) and a piece of 12-14 guage sheet metal that you can weld the stud to and then weld the entire piece of sheet metal to the seat brace. I always reinforce the front seat mounts as they tend to tear the seat brace or rip completely out. I just use thicker washers to reinforce where the stud mounts to the seat brace if the stud is still in good condition.