Welcome to the forum, and congrats on your Jeep! We would love to see some pictures!
For your gas mileage questions, I saw a cold front moved in through Missouri today, so I maybe you had a strong headwind? If your Jeep is rated at 23 highway, then it is the trail rated FDII like I have. The only time I ever got 23 MPG on the highway was when I drove 55-60 mph. When I drive 70-75 I usually get 20-21 MPG, and if there are strong winds and I drive 75, I usually get about 18 MPG. Since you just got the Jeep it's also possible the Tires are a little low, which increases rolling resistance and lowers MPG. In the morning before you drive anywhere, check your cold tire pressure. If you have the FDII, it should be no less than 35 psi... I usually kept mine around 38 PSI cold.
Also, I picked up my Jeep in Virginia and drove it back to Texas. I was shocked when my gas light came on at around 225 miles, and I was afraid I was going to run out. Since then I usually get 240-260 miles a tank, and on one occasion (in the Colorado Rockies) got 308 miles on a tank. The good news is I pretty much always get around 20 MPG in the city