Are there any guidelines when it comes to any of the more spectacular kinds of things people can do within the Harry Potter universe, such as animagus, metamorphimagus, apparition, Half-Breeds, so on, so forth? 

A more on topic question would be whether or not our characters would be suffering the effects of the economic regression, I assume so, but what if one were to write up an opulent pure-blood or a professional Quidditch Player and so on? In more plain terms, are there restrictions oncharacters' former profession?

There's probably more obvious questions I could ask, but I'm oddly tired right now.