Body Work Help

[Chevy Truck Guy 86]

I have never done any body work before, but I am going to attempt it on my build. I have done a lot of research on body work but I still have some questions before I start. One is that where should you use seam sealer? Would you use it on two pieces welded together flush, or would filler take care of that. Also when you grind to bare metal then work on something else is there something you could spray on to prevent rust or should you just sand it off before paint?

[Blazin]

If your worried about rust forming only work one panel at a time.
As afr as seam seal its used where two panels meat each other with spot welds. Or in the case of our beds where the bed side meet the bed floor. They are bolted together.