The best and fastest route is San Luis Potosí, Matehuala Saltillo, Monterrey cross at Colombia, the booth to get your TIP back is very easy to find, As you drive through the complex you will see a small white building on your left, there is an area to pull off the road in front of the building, that is where you return your TIP.
After you exit the US customs head north on the 225 it will take you to I-35
or you can go right on the 1472 which will take you into Laredo, as you enter Laredo there are lots of hotels right along I-35. I usually stay at the Days Inn which just about the first motel you come across.