Others have answered your questions on inbreeding, so I'll touch on the patterns. Some people think that a "hook" on a ball python means they are het for something, or that they have funky genes which could produce something "neat-o". I don't remember where I read this. It may have been the VPI book. Don't quote me. But as far as I know, none of that has really been proven.

As for the other markings, the letter "P" probably means it's het for Pied!!

Just kidding. sorry. I had to.

Really, I haven't heard anything about markings of other shapes. But pastels are usually "jungle" in pattern, which means they're likely to have any number of crazy shapes and patterns. I would just say it's part of his pastel genes and doesn't mean anything fancy.

But, I have no "real" evidence for this. Someone else might have another opinion.