As for the carpet.. if you have a santize option on your washing machine.. that should be hot enough to kill the coccidia. If you don't I would honestly opt for paper towels instead. The dragon poos on the paper.. you pick it up .. wipe up a bit and throw it away.. and you wont have any reproducing coccidia.
The temps.. how big is your current enclosure? The carpet doesn't really help with the temps either... since it doesn't retain heat. I use two heat lamps from lowes for ambient temperature. My hot side is 99-102 and my cool side is 89-95. You don't really want your cool side to be lower than 88 or so, and the cool side really only needs to be a very tiny portion of the enclosure, most of the area should be around 100. I use a halogen flood lamp also from lowes for the basking spot.. it gets to 136. The size of the enclosure really will determine the best way to heat it. Also.. you do have a uv source right? How far away is that from the animals. You want it only about 8 inches away, 10 inches max. A foot or more away has greatly diminishing effects. That also depends on the type of bulb used. If you have a mvb.. that can be around 12 inches away.
Changing the enclosure over and over will stress them out. They need a secure place to hide where they can count on not being disturbed. So get it how you want it and then leave it alone as much as possible. Uros like very low, very tight hiding places. You want maybe a centimeter higher than the animals body.. maybe even less, they really like to squish in there and you want it just big enough for them to turn around in. They are really good at curling around in a U.. so if they are babies.. you want fairly small.. low profile hides.
Ok.. i looked at your pics. Those most certainly are not babies.. nor are they 7months. Previous owner may have had them seven months... but those are somewhere around a year to maybe a year and a half. They are saharan uromastyx.. or U. Geyri. They would be considered subadults. You will eventually want more room for them.. but what you have is fine for now. The basking spot is very high. Do they climb up there? If they are getting up there and using it.. thats great. Uros are not much for climbing though. They like to stalk across their enclosures back and forth. They are usually very active and like to run.. which is why I have a 6 foot by 2 foot 125g fishtank for mine. The flower pot hide is way too high.. even the other hide is higher than I would use.. but for now they are both ok since they provide somewhere to retreat to. You need to eventually find lower hides so that they can build up decent humidity at night... or you may run into shedding issues. My hides are very low.. but somewhat large.. so Gordo is going through serious shedding issues right now. His skin just doesn't want to come off. Since your enclosure is so small.. I am not sure how a heat lamp would do.. But I would try it. You may even be able to use the heat lamp as a basking spot source too. It can heat up the tile significantly.. and then the surrounding area as well. They are super cheap compared to the halogens. I am going to post pictures of my enclosure. Although it isnt beautiful.. it is very optimal for the animal.
This is his whole house. Everything is fairly low. Two heat lamps on either end.. and the halogen pointed at his slate basking spot. UV tube in the middle.. half over the basking spot.
This is his cool side hide, I got rid of the store bought one on top cause he never bothered with it, but he LOVES the one underneath. I also doubled the flooring under it.. so its an even tighter squeeze inside than the opening would suggest.
This is his hot hide where he sleeps. He curls up and tucks into the back of it.