For powering your CB, it's important you connect it directly to the battery to minimize possible radio noise. This is Basic Radio Installation 101. Fuse boxes and aux 12 volt wires like the TJ has available above the glove box will be electrically noisier than the battery will be which will provide good clean pure DC power. By electrically noisy, I mean the kind of noise things like the fuel pump and alternator can cause which a CB can pick up in both what you receive and transmit. I'd run a 14 gauge wire from the radio to the battery, making sure the in-line fuse that came with the radio is kept in place. What gives the same effect as connecting to the battery but is an easier connection to make is the 12 volt stud on the battery-side of the Power Distribution Center, on the passenger-side fenderwell. There is a small cover over it that is unsnapped to expose the stud that has a heavy guage wire that connects directly to the battery. Disconnect the battery first and then undo that nut so you can attach the +12 volt lead from the CB to it.
Actually you will have two +12 volt leads coming out of the CB plus the black ground wire, one of the +12 volt leads is meant to to provide unswitched power all the time to the CB which keeps the CB's memory (like the last CB channel you were on) alive. That lead goes to a constantly on power source, like what I described above.
The other +12 volt lead is made to be connected to a switched source of power that shuts off when you turn the ignition off. I would not connect this lead to a switched power source since there will be times you want the CB on but you will not want the ignition turned on or your key in the ignition... like you're on the trail and want to hear the CB while you're outside of the Jeep. I prefer connecting that lead to the same non-switched source of power the other lead goes to so the CB can be turned on at any time.
No worries about the CB draining the battery if you forget to turn if off. That huge battery could power a CB literally for weeks without being drained.
I second the recommendation for a Firestik antenna, they're very rugged and because they don't sway too much like some other antennas do, it's ideal for rough trails. Be sure, if you get a Firestik, to get the "tunable tip" version which just makes it a lot easier to tune due to a brass tuning screw it includes. Personally I'm running a 2' version of that antenna which works fine on the trail, seemingly as good as the 3' it replaced when my Jeep would no longer fit in the garage with a 3' antenna.