Store them inside after cooking. (let them cool down first). I put them back on after starting the coals and give them about 5 mins and then use a wire brush and then spray them with oil again, and wait about 5 minutes before putting meat on.
I am assuming you mean Loins and not tenderloins as you want to cut them into chops. I do mine around 325* (as the loins are usually pretty lean) for a bit over an hour and get an internal temp about 145-150 and let rest.
If you are having problems finding plate ribs. Ask at the supermarket if they have the ribs they cut up for shortribs or Korean style ribs. They probably have them cryovaced in the back and cut them up to the short ribs and Korean style. I've been buying them this way for months now.
It all depends upon your tastes (and what your family or whoever you are cooking for). Experiment, try things that people suggest and find out what you and the people you are cooking for like. When it comes to BBQ, nothing is really set in stone.