Some questions about railroads.

I am hoping there are some railroad buffs here.

I got to thinking about railroads after listening to CSX radio ads. So let me start by asking some questions about CSX.
Why have I not heard of them before?
How long have they been around?
Who are their ads intended for?

Some more general questions:
Do railroads own the tracks they run on?
Do they ever share stretches of track with other railroads?
Do railroads pay taxes on the land that the tracks go across?

In general, how much choice do companies have in selecting a railroad?

If a company wants freight shipped by rail, does the company have to work with both the railroad and the trucking companies that move freight to and from the railroad?

Direct rail access may not be so important now, but it must have been before automobiles. Have there been cases where cities would offer incentives for a railroad to build a depot near them?