Selecting my name

Hey all, I just finished the three hours it takes to patch this game and went on to make a character...my first hitch came up at the character select, not only was I disallowed to use my uncle's name in my character name (jesus) but then any other name I tried (various attempts at spin-offs and modifications, so far as to look up alternative spellings for some of the words) was supposedly "already in use". My questions for you are as follows:

How long can my character's name be?
What are the phrases or words that are disallowed?
What kind of ninny prohibits using as common a name as "Jesus" in one's username?
How do I know if my name is actually already taken?

Thanks for your time all! Hope to see you all soon.