Car Audio FM coax and plug

So when I decided to put my CB antenna in the stock location I thought I wouldn't miss FM radio. I was wrong.

So now I'm planning on running another antenna on the driver's side for FM, and have two questions:

1. What is the nomenclature of the male connector that plugs into the head unit
2. What impedance is the coax suppose to be? 50 or 75 ohm?

Thanks!