You will have to contact the factory.
Made in Czechoslovakia, Brno is now in the Czech Republic.
some are, some are not. That is a make of rifle, not a model.
From my experience, BRNO rifles are very nice. They are no longer made under the name BRNO, but CZ, and although the manufacturing processes may have changed, the CZs are near identical to their BRNO ancestors. Try to get a BRNO model 2.
10-1000 USD depending on specifics
Assuming you mean a Brno 602, it will depend on the caliber that the rifle is made in. Brno 602 is a make and model, not caliber.
You need to talk to a gunsmith.
Used, yes, New retail, doubtful
15 million dollars
I do not have a historical price listing for the exact rifle you asked about, but in general, the BRNO rifles tend to be fairly high dollar- as with ANY firearm, value is driven by exact model and condition. I would urge you to get a face-to-face evaluation from a dealer or gunsmith familiar with these rifles. Sorry- wish I could give you a specific value, but just do not have much info on these in my reference library.
Brno is famous for its history places.
Brno is in Czechoslovakia, Essen is a city in Germany. Two different countries. "fluss stahl" refers to "fluid steel" made by KRUPP Industries located in Essen, Germany. Since Krupp was one of the premier manufacturers of high quality steel products in Germany prior to (as well as after) WW2, there is a good chance that Brno used KRUPP steel to produce rifle barrels. Especially in the late 1930s.
Brno Kabužić died in 1855.