The contact should be easy to remove using the hair dryer method - Try a test spot first. Check to see if there is any evidence of wear under the contact. What ops used to do is apply contact or mylar AFTER the machine was on route - now if the playfield sustained wear to the point of flaking (or close to), then removing the contact will remove paint. So you need to be careful.
In most cases - it is easy to remove old mylar off EMs, as the mylar is in fact "contact" and the adhesive is not "sticking" any longer. Having said that - Check a test spot first !
"Gottlieb White" - It is closer to an "off white" - semi gloss. Don't use a flat white unless all the paints you are using are flat AND you wish to clearcoat using a semi gloss.
The base is going to be a bit of an issue for you. The wood is easily obtained at bunnings - but you may have to remove the back panel to do it properly. Removal is easy - but re assembly is difficult without the right tools ! You COULD try using thinner wood, and bending it into the grooves of the sides of the cabinet.
