Your gun should have a model marked on the upper tang, behind the hammer. There may be a flip up tang sight mounted there with two screws which will have to be removed to find the model. The model 1893, and 1894 both had the barrel markings you described, so it's hard to say what your gun is, let alone what it's worth, until we know for sure. A bore of about 7/16" could be a .38-55, or a .38-40. The caliber should also be marked on the barrel top, just in front of the receiver.
You will have to define who "they" is.
It is: 135 degrees
None, since there is no such word. But an octagon has 8 corners.
An Octogon has the same number of sides as an octopus has arms.
The octagon has 8 angles in every grade.
45 degrees/angle for a regular octagon.350/8=45.
An octagon is made up from six triangles each containing 180 degrees.
If it is a regular octagon it's 1080 degrees. You can use this formula: S = (n-2) x 180
20 diagonals in Octagan. For n-sided polygon, no of diagonals = (n choose 2 ) - n = 8C2 - 8 = 28 - 8 = 20
It sounds like you have a "Yellow Boy" Winchester 66, and is the Fourth Model since it is centerfire. It the serial number is between 149000 and 170101, that proves it. It has a minimum value of $1,000 if it is even in one scraggly, rusted piece (a 10% gun), and could be worth upwards of $9,000 it it has most of the blue, good yellow color, the wood is good, and it shoots good (a 90% gun). You definitely need it appraised by a professional gun appraiser it it is an excellent gun.