Many restaurants let people pay when they pick up or get the food delivered. So doing this costs the restaurant money, not OP. That's why he's spoofing his info too, if he paid they probably wouldn't care enough to ban the number.
I am not quite sure what the joke is about, could you explain? Those helmets seem to be used for preventing injuries in case of health conditions like epilepsy, but I can't make a connection at all
They're saying OP is slow and the helmet is there to prevent them from hurting themselves in the future.
OP isn't paying for the order, they're ordering over the phone for local pickup, which means they'd pay when they arrive. And OP isn't going to the store for pickup...