Some common caliber's used for hunting are .308, 30-06. It all depends on what you are hunting. Personally I would recommend a .308, especially for a beginner. It's a common enough round and there are a number of widely supported rifles that can be chambered in .308. In addition it's somewhat on the smaller end of big game caliber's, if you plan on just getting small game or varmint hunting you might look into something smaller, but if not stay above .308.
flintlock rifles
No.... You can only hunt with 1 rifle at a time
Depends on your state. Some states allow hunting with semi auto rifles, and some don't.
A caliber of rifles commonly used to hunt deer and elk.
You will need to contact the State Department of Natural Resources to find out.
Some do carry rifles, yes.
The straight is better for accuracy, but pistol is more comfortable for sustained fire (like target practice.) I prefer pistol 'cause that's what I hunt with.
You will need to check the games laws in the states you wish to hunt in- we cannot post all of the regulations for all of the states. SOME states (Pennysylvania being one) do NOT permit the use of semi-auto rifles for big game hunting.
Double Star and CMMG's bargain bin rifles. Some DPMS rifles, as well.
Maybe. They may be used to take small game, but not deer. They may not be used to hunt migratory birds, such as dove, ducks, or geese. Semi-automatic rifles may not be used. So if you want to squirrel hunt with a bolt action .22, you should be legal.
Prior to 1968, some inexpensive .22 rifles were not serialized.
Some are.