PM stands for Private Message. We can send messages to other forum members. Unfortunately, the number you can keep in your mailbox is very small, so my box is always filled up. I guess I'll have to learn to export files, as deadpixel suggested, or just delete them and not worry about it.
I have no idea what is a good partner for Shatterfrost. I just pair it up with something I am being asked to breed with for a bingo task and take my chances. I can't remember what I bred him with, darn it, but I ended up with an enamored dragon, which is only 5 hours. It was definitely not what I expected to come with that pairing, whatever it was.