XJ550R fork oil change

Hey! Been a while since I've had the time/$$ to do anything with the bike, and since I still don't really have the $$, I'm starting off with what I hope is the inexpensive stuff. To wit...

1. I wanna change the fork oil. I can guarantee it hasn't been done since I bought the bike... and it's a pretty fair bet that the yabbo who owned it before I did never changed it, either - judging from the state of everything else when I bought it. I've done some poking around so I have a fair grasp of the procedure, but I wanted to check and ask wiser heads than mine (i.e. all youse guys) what parts, exactly, do I all need to have on-hand before I start this? Whatever I'll need, I'll gladly order from Chacal, I just don't wanna start this and find out when the caps are off that I just needed ooooooone more part to put everything back together.

2. The bike rides bumpy - always has - and I'm sure that part of it is my big tuckuss puts more weight on it than the kids it was originally marketed to. On the other hand, I'm pretty sure it might also have something to do with the original rear shocks still being on the bike as well. Is there some (cheap) way to test them, or should I just assume they're not working right? And if that's the case, can they be fixed/recharged, or am I better off just buying new shocks based on the original specs?

I'll appreciate any info y'all can offer - this forum and its members are the main reason my bike's still on the road in the first place!