LairdScooby

I'd have a look online in your home area (it says non-UK so no idea where in the world you are) and find a Dexron VI compatible fluid and use that, especially if you plan on periodic part-changes or full changes to maintain it. A quick search revealed that Pentosil #1 is a "life-time fluid" so is likely to be more expensive and won't necessarily last the life of your box. I'd prefer to do a part-change once a year or so to maintain the fluid than use a "lifetime fluid" that maybe breaks down and kills my gearbox. Each to their own though.......

I believe the later S Types use a ZF gearbox so you should be fine with a Dexron 6 fluid or equivalent. Is there a reason cited for the use of Pentosil #1?

Depending where exactly the material has come loose, you may be able to make an in-situ repair using adhesive carpet spray - hold the headlining away from the backing board (biscuit) and spray some glue onto the biscuit. Let the glue "flash off" then carefully and progressively fit the liner back onto it. I've used this trick on many cars over the years and it usually works well. However, if yours is truly horrible, you may have to bite the bullet and take the complete headlining down.

Nervous

Panic

Claustrophobia

Little tip with the inertia switch - tap the body of it with the handle of a screwdriver until you hear it deploy with a definite "bah-doy-nnng" then reset it. They have a habit of furring the contacts, especially if sat for a while and this can often cause the fuel pump to not run. Also try the spare key in case the transponder in your main key has died.

The fuel pump isn't always noticeable when you switch the ignition on so i'd suggest you get someone who has the necessary diagnostic equipment to troubleshoot. You could spend a lot of time (and money!) firing the parts cannon at it without getting any results. It may be something much more simple like the CPS (crankshaft position sensor) causing your non-start.

What diagnostics have you done?

Timeline

Welcome aboard and if you don't mind sacrificing a spanner to make it an "S" shape, it apparently makes changing the oil p sender much easier. Not done it myself but saw such a spanner ~25 years ago in my local Jag specialists when i was buying a car from them (XJ40 3.6 Sovereign) - luckily mine didn't fail during my ownership.

Digital (Digital Disarray was the name of a website i used to visit occasionally many moons ago)

Have you tried the spare key? It sounds like an immobiliser problem to me, specifically the system is no longer recognising the key so the spare may well work. There may be other causes but give the spare key a try first.

Many independent motor factors will mix to a colour sample as will many automotive paint suppliers. Normally the gadget they have that analyses the colour is hand-held so you should be able to get a match just by driving your car there.

Chaos