1. I'm pretty sure they are going for Roman Numerals on that one, i.e. V=5. There's alot of references to the number 5 in their lyrics "power of five", "five align", etc.
2. I believe it's based on a book of the same name. No idea for sure, as I haven't actually read the book itself.
3. Because they rule. Hahaha... I can't remember why, but I think it's on Symphony X's website in the FAQ section.