Welcome!
If you haven't already found them, owners & service manuals can be found by clicking the 'Manuals and Specsheets' link at the top of any page.
Welcome! The nice thing about all the gear you mentioned is that it's fully serviceable and restorable for a lifetime of enjoyment. I'm looking forward to following your progress.
Welcome!
In addition to the fine pre-amps that @Sk1Bum mentioned, also take a look at the Carver CT-7. It's a very nice performer and the remote control is a nice modern touch.
Welcome! As @Half Life pointed out, schematics for Sunfire gear aren't readily available, so good luck with a search. The sub is definitely worth saving.
Welcome! In addition to the manual link already posted by @Sk1Bum, do a search here on those model numbers and you'll get some good troubleshooting info.