They are the arms of an angle.
Yes when two lines share a common end point an angle is formed
The only lines that are in the same plane that do not intersect are: 1. Lines of finite length (eg 1 6" line on the floor at one end of the room and another 8" line at the other end) 2. Parallel lines
a rainbow 
an angle
When applied to two line segments, they are said to be congruent if they are both exactly the same length, but they need not be parallel to each other (they can also bisect each other). Thickness does not matter as lines have no thickness (thickness only applies to shapes). However, it should be noted that rays and lines are not congruent as their lengths are infinite. Rays have no defined end point while lines have neither a start nor an end point defined. Line segments always have both a start and an end point defined.
The vertex.
They are the arms of an angle.
Yes when two lines share a common end point an angle is formed
The points are Dependent. Just pot the points and put two arrows at the end of the lines.
It might depend on how you draw it, but I don't think it is possible. Draw the figure, and look at the points where lines meet. Count how many of those points are "odd", meaning that an odd number of lines meets there. Each of these points has to be either the starting point, or the end point, and you can only have one starting point and one end point.
Yes, an Octagon does have a center point. The easiest way for me to find this is by drawing lines between opposite vertexes. You should end up with four lines and they should be crossing at one point. That is your center point! :V
The only lines that are in the same plane that do not intersect are: 1. Lines of finite length (eg 1 6" line on the floor at one end of the room and another 8" line at the other end) 2. Parallel lines
No, not all meridians have the same length or the same beginning and end points. Meridians are imaginary lines on the Earth's surface that run from the North Pole to the South Pole. The prime meridian, which passes through Greenwich, England, is considered the starting point for measuring longitude.
two lines intersect at point b which is also end point of two rays
An anchor pylon is an end point which utilizes horizontal insulators and occur at the end points of high-power transmission lines.
Kirchof's Law - the voltages are measured between the same starting-point and end-point.