Blue with adjustable sights - $75-$125 in NRA Excellent Condition - Less $ if not excellent. Not a bad gun, but $0 value as a collectable.
It is a dual action revolver
It is a cheap German-made revolver of uncertain quality.
Try e-gunparts.com
50-165 USD
Check the owner's manual. If you don't have one, take it to a gunsmith and ask for help
If it's made out of gold, weigh it and use the daily spot price of gold to determine value. If gold plated, about 200 USD.
25-200
50-500 usd
Internet, gun shop, gun show, want ads.
@50 or so
Somewhere between $1000 and $3000