Since I just completed my way through this process, I'll share my experiences and you can take it for what it's worth.
First, CB mounting. I just received my "Brolin" mount Saturday, and installed it right away. It works exactly as advertised, and is a very nice piece. I'm very pleased with it, and would recommend it.
Second, the radio. You need to decide how serious of a "radio" guy you are, and what level of performance you want. I am not a "radio guy" by any stretch. I just wanted a full-size, big-rig style radio, that looks cool, and provides a measure of "entertainment" with decent performance while on the road (keep in mind that the antenna and antenna mounting scheme has more to do with overall performance than the radio itself). I bought a Cobra 29 series, with all the bells and whistles - Nightwatch, Sound Tracker, weather bands, etc. It looks great and seems to work fine. Does one need or want that stuff? Maybe, maybe-not. After I had bought the unit, I started doing some research

rolleyes

. I talked with a guy at a local CB shop, and he told me that the current Cobra models should be just fine for most casual users, but they are not made by the same manufacturer as the "Classic" Cobras of old were, which apparently were of better quality/performance. In fact, he told me that the Uniden P76 series, IS the old Classic Cobra radio. Beyond this, there are people who "supercharge" the transmitting power via amplifiers in excess of the FCC maximum of 4 watts. If you follow the high road, this practice is illegal in the US. Apparently, there are loopholes, though. You can mail order what are called "export" radios - radios designed to be sold outside the US (and FCC jurisdiction), which have higher transmitting power. I don't know much more beyond this about them. For me, I don't really care if my CB can transmit 4 miles or 8 miles. I'm not after legal troubles with the FCC.
Third, the antenna system. I chose to go with a 3' Firestik antenna w/ adjustable tip, and one of their custom made-for-Rams stainless steel fender mounts. It's a very nicely done set-up that doesn't look too obnoxious. I chose this because drilling a hole in my roof for a permanent mount was not an option, and I didn't want to deal with magnetic mounts, either.
My total outlay for the radio, antenna system, and the "Brolin" mount was $258. Overall, I am very pleased with everything.
Hope this helps. I'm sure some of the members wiser than me on this subject will join in. Good luck.