Parts of the building date back to the 1200s, but the part in the photos above is from the 1600s. The render is over stones and mortar. Some of the stone is cut to look like brick, but it is mostly stone. The render is a sand rander of some sort to give it the colour. I personally don't like it and wanted to take it all off and expose the stone, but the cost to do it was astronomical. In shoirt, some of the building is original stone, some is cut stone, and some is your bog standard red brick (or the Somerset equivalent). We do have lime render on the walls of the front door. We originally had damp all through that wall in the living room until a plasterer noticed it was a concrete render (put there by builders fixing a wall that was crushed by a fallen tree). So, we had the cement render taken off and lime render put on.. and in about a week, there was no more damp!
Re the wireless access points - they were approved by the listed building officer. For small things like that, it is a simple application, some photos and a yes or a no. There is no cost (unless you want to challenge their no). As the place had most of its original interior features sold off before it was listed, the listed building officer is very reasonable - well that and the fact we have restored a lot of the building to its former glory (e.g. taking out all the PVC windows and replacing with wood - can't remember the type but apparently what would have been used in the last extension of the place in the 1800s).