I'd say grab a pair of seats from a loaded leather pickup like an SS or something, those would look awesome. As far as this "solvent" you're speaking of, I've never heard of such a thing, there are dyes that can be used to change the color of an interior though. IMO, I'd leave it the color it is and rather color match (paint) some of the interior pieces like the dash bezel and door components, etc.
For your debadge, I'd recommend some strong fishing line wrapped around two dowels and some Goo Gone. Fishing line works great for getting under the badges and cutting through the adhesive. Then some good ol' Goo Gone and elbow grease will get the remaining residue off, unless you want to get one of these: iTOOLNET.COM | 3M STRIPE WHEELS | 3M 07499 at your local parts store.
2001 GMC Sierra SL ECSB - Project
2012 Honda Civic Si - DD
2009 GMC Sierra SLT ECSB - Sold