General critique. Please do not take this as an offense or attack.

- Grammar should be a greater focus. In Advanced, it's expected that you write with proper structure and punctuation even in a CS.
- 60 is actually quite young. For his Age Appearance, he would probably be closer to 100-120 (depending on his Reiryoku).
- Were his parents part of the Gotei? That would be the only way he'd be able to pull pranks on the Captains and such.
- Why was Kella abandoned by the Gotei? Was she exiled or did she leave? If she would not reveal the reason, it would be good to add that. Would it have been allowed for him to trained by an ex-Shinigami? Did she seem to delve into dishonest practices?
- She would not have been able to become a Hollow in the Spirit World. Only Pluses from the World of the Living can become Hollow under volatile circumstances. Was this a doing by a third party? Did the 12th Division discover this? How much was it looked into?
- "Quickly" rising up the ranks is neither realistic nor interesting. It's better (in RPing practice and general "reality" in a fantasy world) if he worked his way up with constant training and over a "longer" period of time.
- The Stats need to be worked over. First, being a "Legend" in Kido while being the Lieutenant of the 11th Division would likely be disallowed if not frowned upon and shunned. Second, anyone below Captain cannot have Legendary stats. Third, it doesn't look like you went through any of the math or calculations for the stats. Something like this would be more accurate to what is possible for your character:
3: 2, 3
4: 4, 2, 3
0: 0, 0, 0
3: 2, 4
2: 2
Even so, it should be described how he "got away" with practicing Kido to such a degree while being in the 11th Division.
- It's unusual for a Zanpakuto to be Italian (or anything other than Japanese). Why is this? How did he overcome the potential communication/cultural barrier?
- The Zanpakuto does not follow the Release rules. The first and second abilities of both the Shikai and Bankai are not related to the theme of the Zanpakuto. Only the first of each are legal considering the Zanpakuto's nature of Acid. Furthermore, the Shikai ability would not be able to transfer into Bankai due to the altered nature of the ability. Lastly, Stats cannot be added during Bankai, they are only reached from what you have already calculated.

If you have any questions about the OP rules and structures, please don't hesitate to ask. :)
I added his name to the roster but I did not link it. Once it's approved, it will be linked.