My pp isn't at PB but he is in a maximum security prison. They do not allow glitter or stickers also. I keep letters plain and simple for the most part. The best thing is to follow asha's advice and ask your pp what you can and can't write about. Onto your second question, all the letters I get from my pp are stamped also but I believe they do it after the inmate drops them in the mail, mainly for people on the outside to know what they are receiving.