Hi Dorn,
If you do a search on here, you will find lots of discussions on leaf Springs. Mine appear to be fairly new and are in excellent condition. I think that there are many different thoughts on what to use to lube the leafs. I like the idea of using the old engine oil...I think it was Randall on here who aslo experimented with putting some material between the leaves..he might be able to expand on that or you might find it in a search.
Yes, looks like the body shop was having some alignment issues and decided to drill so extra holes. Once you decide what holes to use you can weld up the other holes to close them.
Good luck with your project.
Cheers
M. Pied Lourd