First off, try a search. Then do your homework. There is alot of info out there. The new thing is body solder, try a search on that. It's actually lead free, so less harmful to you. It takes dicipline but it's worth it. And look into a friction disc for the dings.
Lead would be used after the holes are welded, not for filling holes. Look for the video of Bill Hines leading a trunk and George Barris acting like George Barris. It will give you an idea of difficulty and such. Lots of stuff to buy for a few holes. If you are into the learning part then the cost would be justified. Use the search with Hines or Barris name and see if it pops up.
if you are looking for a shop that does lead work, go to Cl***ic Cars of Houston in the Bellaire area. They do lead work there and have a guy that is very good, He learned it from Bill Hines himself..... their number is 713-838-9700
One of the most important steps in leading is killing the acid when you are done. I've seen some nice jobs that this step wasn't completed adequately; which caused rust underneath an expensive paint job. The fix then was to take the car back down to metal and start over.
Wear a mask when working it.....I know it shows them on American Hot Rod, filing and sanding lead without any masks, but it will cause you problems a lot worse than a bad paint job. I have used lead a few times and the important thing is get the right gear and practice on something first before attacking the body...there are no shortcuts, and cleanliness is paramount.Get onto youtube and try and find old Roy Shmitt (?) who worked at Boyds doing some leadwork..amazing old craftsman who makes it look simple.Good luck and let us know how you get on.