Top 10 mysteries of Bleach (Spoilers)

In no particular order, these are the ten mysteries that interest me the most.

1. How does Yoruichi turn into a cat?
2. How are zanpakatous formed?
3. Why can souls be blind or have tuberculosis?
4. Is Urahara Kisuke a Vizard?
5. What squad was Isshin a captain of?
6. Why is Komamura Sajin an anthromorphic wolf?
7. How did Kukaku Shiba lose her right arm?
8. Who are the Four Great noble families, and who are the lesser nobles?
9. Who would win in a fight between Byakuya and Kenpachi?
10. Why do the obviously powerful Urahara, Yoruichi, Ryuuken, and Isshin leave all the hard work to everyone else (Ichigo, Rukia, Ishida, etc.)?

If you have answers, post up. If you have questions of your own, post those as well. Let's see if we can't get some interesting theories here.

the answer for 9 is byakuya because he is smarter and faster
and 10. because they are lazy XD

10. Why waste the powerhouses when most battles don't require the full potential of Urahara and others. I would really like to see more Urahara in battles though.

Someone posted this on an anime forum I frequent, and I think it's a very good point.

Unohana is very strong and perceptive she was the only one to realize what Aizen was doing and the truth about his shikai's abilities, also it is usually those with power who love peace such as Shunsui, Ukitake, Unohana, Orihime, Urahara, Yoruichi and Yamamoto but those who do not have it continue to fight such as Grimm, Nnoitora

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I may be biased but I think Yoruichi and Urahara are both way stronger than people might think. Yoruichi for example went into the fight with Yammi without bothering to use shunko, a zanpakuto, or bankai. From that I think that she must not have to use more than that to defeat most enemies. If you were able to beat almost everyone you previously fought at a minimum of your power, why would you do more than that? Now that she knows what she is up against, I'm sure she won't hold back in her next battle if she goes up against an Espada again (like Halibel, perhaps? )

I am really looking forward to see how the fight against Aizen plays out, and if any of these questions are answered.