Howdy, all!

So, after looking at them for a year or 2, I made the jump from my 1995 S6 to a 2003 RS6. (UrS6 is for sale if anyone wants one. Needs a little help, but has a lot of mods.)

I have never owned a V8, nor an automatic, and I gotta say, both are actually awesome in the context of this car.
She's black on black, 88k miles, #905570, near perfect condition, and all service records from new! All services were done on time or early, and the last owner took exceptional care of her (he traded it to a private dealer for a '15 S8). So far, all I've done is tint it (Florida - requirement), and I have a set of smoked Hella tails on the way from Europe. I have never named a car before, but this one came to me like a bolt of lightning. His name is Derrick Lewis. UFC Fans should get it.

Pics:
https://imgur.com/a/pI3cgoH

I have a few questions, though:
-Are there any places to source a belly pan for less than $500?
-Screws for the airbox: Mine are rusty. I haven't pulled one yet, but is this just a standard fastener I can order in SS from McMaster-Carr or wherever?
-VC's are weeping, though they were replaced about 5k miles ago seems like it's a semi-common issue? Should I try to tighten the bolts? Just tighter, or is there a torque spec?
-One intercooler is weeping, so I need Wagners, right?
-My LCD in the cluster is fading when hot (super common, I know) has anyone tried the ColorMFA? It seems pretty cool!
-Should I be changing trans fluid now? every factory service has been done, but I didn't see that as a factory recommended service. If I should, I want Fuchs Titan Sinto something, right? Thought I saw that somewhere.
-My car has the Sound Enhancing Exhaust option. To my understanding, an aftermarket exhaust won't really net any additional power, but makes fun noises? If so, I'll probably leave it. She's a sleeper for a reason. I half want to put an A6 or S6 badge on it, but put it on slightly crooked and see if anyone notices.
-I need to go through all vacuum hoses. I can see the one on the EGR has started to degrade. Are there any other rubber type things I should definitely replace at this interval? If it wasn't in the factory service manual, it hasn't really been done. I assume standard 5mm german vac hose is fine?
-Does anyone other than 034 make a tip chip? I emailed MTM, and got no response, and I even emailed them in German! Does the tip chip adversely impact longevity of the trans?
EDIT: Forgot one!
-The headliner has a 2-3 spots the size of the palm of my hand where it has dropped. Any recourse that does not involve pulling the headliner? If I have to pull it, can I peel back the alcantara and re-glue it?

This whole forum has been my go-to place to learn about these things! I haven't yet had the room and the balls simultaneously to really get on it, but one 95% throttle pull from a stop to 100 was pretty freakin cool!

Thanks!
-Brad