You might want to check the Winnebago Owners forum here - maybe some other Vectra owner has done something similar.
The specific techniques for construction depend on the year and floor plan, so what I did when I upgraded my 2004's tvs is pretty much irrelevant to your 95 Vectra.
Full body paint is a roughly $10,000-$12,000 upgrade. There are shops that can do an excellent job in various parts of the country. Where do you want to get the work done?
I know a guy who travels around and does great flooring work. Ernie Ekberg - see his Yahoo group here:
erniesremodelingandrepair : Ernie Ekberg's Floor covering
Some excellent flooring photos there.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL