100-1000 and up depending on specifics
No- the 7x57 was developed separately, in 1892 by Paul Mauser. The 8mm Mauser (actually the 7.92 Mauser, but every calls it the 8mm) was developed by a government board.
Numerous commercial and custom makers have made 8mm Mauser rifles in the last 100 years
$175 to $800 depending on condition and matching parts.
What about it?
No
The 8mm Mauser is a good black bear round. American 8mm is kind of underpowered but with handloading or European ammo its in the same class as 30-06..
Minor collector's interest- .50 to 1.50, depending on condition. There are some supplies of Nazi marked 8mm Mauser still turning up for sale.
Yes....
10000.00
$450
value depends on overall condition................
No, you cannot shoot .270 Winchester ammunition in an 8mm Mauser firearm. The .270 Winchester has a different case size and bullet diameter compared to the 8mm Mauser, which is designed for 8x57mm Mauser cartridges. Attempting to fire the wrong caliber can be dangerous and could damage the firearm or cause injury. Always use the correct ammunition specified for your firearm.