Hi, the reflector blankets you are asking about are called "pop up gizmos"... Aka "pugs"; do a search for that and you'll find the website that sells them.
They seem expensive but are on my wish-list. I think $2 survival blankets and some bungee cords would probably be similarly effective.
You can also buy reflectix at Home Depot which you can cut to size to fit in your zip up windows.
With regards to cable tv, you can buy a cable tv cable at your local electronic store or radio shack type store. You should find a connection port on the outside of your htt usually near all your other hook up things