Taking 50 minutes to load 3 threads on BF so I'm not going to look for the original posts, no clue if they got responded to already.
psimet - unofficially you have to issue 1099s. These are considered offset on cost of goods, i.e. $1000 paid for wheels, minus $100, means wheels are $900 cost. There is no need for the rebate receiver to "put" the 1099 anywhere, they just have to show that for the $900 wheels, they paid a net total of $900, not $1000. But if it's over $600, you need to issue them. That's for customers/clients and such, not for utilities etc.
I helped someone with dealing with papers her husband had saved. Found stuff from 1948, GI Bill stuff. I learned much later (2 years?) that their son was my teammate about 20 years ago. Small world. As far as how long I save things, I just ask the wife on "saving stuff" questions. USAC is 10 years though, that's what they say.