1. I am replacing floorboards in my Valiant. What should I use on the frame rails before welding the new ones in to seal the metal? They have the typical surface rust on them.

2. To replicate factory spot welds, would a stud welding gun be a good choice? This is not a rare car, so I am not looking for exact factory replication. but don't want to puddle or mound with a mig in place of the factory spot welds.

3. Widening my rear wheel wells (mini tubbing). What would be a good seam sealer to use?

Thanks!
Brian