You can get your permit to drive the tractor trailer combos as early as 18 years old.
No, you can't.
Yes
No, you cannot.
No, not legally.
You need a Class A learner's permit.
An 18 wheeler consists of a tractor (meaning something that pulls) and a trailer (meaning something that follows.) A semi tractor-trailer rig has a trailer that sits on top of the frame of the tractor on a coupling device called a "fifth wheel." The tractor has ten wheels with two on the front axle and four on each drive axle in the rear. The trailer has two axles with 4 wheels each. The tractor and trailer together are informally called a rig. Is that what you were after?
What kind of a tractor is being asked about. A farm implement or a semi-trailer hauler
There is really no courses on learing to drive a tractor trailer, however you can get information online or maybe if you know someone who has a tractor trailor you can practice with theirs.
Not individually, but the vehicle they drive must be insured.
There are a variety of tips in order to avoid tractor trailer accidents. Some of these tips are for the driver not to drive longer than they can physically stand. If they need to take a break, then they should.
no no yes yes
You can legally drive an agricultural tractor unaccompanied at the age of 16 years old, only to and from a tractor driving test. At the age of 17 years, if the tractor has two seats then a qualified driver must accompany you, if the tractor only has one seat then you can drive unsupervised. In both cases L plates must be displayed. If driving on a provisional, the tractor width must be 2.45m or less and if pulling a trailer, the trailer must be single axle and width must be 2.45m or less.