floor pans

I have purchased a new welder and started cutting out the floor pans
any advice for a. Total rookie. I have watched videos and been reading articles. My plans include taking the old pans to practice on. I will have to find the proper primer to use before welding, . After welding, and sealing the seams, will epoxy primer suffice or should I apply a coat of paint before placing a sound and heat barrier. Hope to have this complete in the next couple of weeks. I thought when I retired I would have plenty of time
Doesn't work that way.