More accurate than 90 percent of the people who will shoot it.
Depends on caliber. www.countrygunsmith.net
The "rate of twist on rifling" is caliber specific. To give you an answer we would need to know which cartridge the rifle is chambered for.
twist is 1:9
1/12
It will vary with caliber.
Impossible to answer without knowing the caliber.
the rate of twist i probably 9" or 1 in 9" not to sure.
The twist rate in a Winchester 670, 243 caliber is 1:10.
1 in 10
Odds are 1 in 8
1-in-66" barrel twist is a Kentucky rifle, not a Hawken. The Hawken brothers used a lot faster twist than that; you needed it for the prairies. Googling "Kentucky Rifle kits" will give you several makers of these rifles in kit form. As to legality for hunting? Any muzzle loading rifle that's at least 50 caliber is legal to hunt with in Idaho.
Most black powder bores have a twist that is relatively slow. Say 1:36 or 1:50. They were 1:48 twist in 45 and 50 caliber