They did come with a small back seat and you can buy them and install it if there is not one in it. Most Jeeps, CJ5, CJ7 and newer Wranglers really only fit 4. Two up front in buckets and two in the back. The back seat also tumbles forward if you need more room in the back and you don't have passengers. I have had car seats in the back of my Jeep and the kids do fine. There is only lap belts in this Jeep. Again, you can install them if they are not in the back.
You probably won't want to spend much time on the freeway but around town and up in the woods it is great! If it is only the three of you you might have room left over for a lunch box or a small dog!
Have fun!