Metal Replacement

I am a shop teacher and welder by trade. I am considering subitting my 73' 240Z to my class as a shop project, but have never tackled an autobody project until now. I have a 73' 240Z which requires new rockers, and both rear quarter patches. My question's for the rockers are:

Plug welding vs seam welding the entire rocker?,

The best way to seal the metal in behind the rocker (weldable paint, ect)?,

Things to take in to consideration when cutting out the rear quarter patches, gas tank, ect.?

I should think I have the neccessary tools, I just need a little orientation. Any information would be greatly appreciated.