Take a cleaning rod with a non-rotating brush, push it into the muzzle about four inches and stop, mark a line on the cleaning rod with a magic marker right at the muzzle, put a tape flag at the end of the cleaning rod or at least 16" from muzzle, push down on the rod and watch the rotation of the flag, when it has made one revolution, stop pushing, put a mark on the rod at the muzzle, pull the rod out , measure from one mark to the other and you will have the rate of twist for your rifle.
In all likelihood, it will be 1:9.5
Odds are 1 in 8
100-450 or so
$600-$900. depending on exact rifle, exact condition. Nice rifles.
It will be marked on the barrel.
1 turn in 9.6 inches
100-1000 depending on specifics
No way to answer without a serial number.
100-1500 depending on specifics
100-1000 USD
300-450
100-1000 depending on specifics
Should be from 1970-1971.