The gold inlay is probably "crayon applied;" that is, there are application rub-on "crayons" in different colors for exactly this sort of thing. Eventually, through wear or cleaning, the "inlay" wears off, and needs to be re-applied.
Alternatively, of course, it could be real gold inlay applied by a jeweler or engraver, but I frankly doubt that that's the case here.
I wouldn't worry about determining the origin of the springs-that it's smoother (and possibly lighter) is a good indicator that the previous owner either performed an action job, or replaced the springs with lighter weight ones than the original, or both. If you're satisfied with the pull weight, I'd simply suggest testing the gun for reliability with a variety of ammunition; CCI primers are reputedly the hardest/most challenging, so if it'll handle CCI cartridges, you're probably good to go across the board.
You can always get Wolff's GP100 Spring Pack, which will give you a variety of mainspring and trigger return springs; a good start point (and where many stay) is to go with the 12 lb mainspring and the 10 lb trigger return spring. Those weights usually give you reliability plus a lighter triggerpull than the OEM 14 lb mainspring and 11 lb trigger return spring.
Again, you've got a handsome package-should be a keeper.
Best, Jon