Welcome to the Cast Iron Chef world. We enjoy it.
We use a wet paper towel to wash and wipe off the soot then stow it. No big deal. Then we toss the paper towel into the fire pit to burn. The sand is a good idea if you are boondocking and don't have a water connection.
Cast iron is tough. The only thing you need to be cautious about is to avoid running cold water over a hot pot or pan. The temperature shock will crack it.
Don't let the myths running around the internet run your life when it comes to cast iron. You can use metal utensils and chain-mail scrubbers on it, just don't use chisels and hammers.