yo Stri, with regards to your spoiler post: if it's a wave of the same stuff we see here: http://www.mangatoshokan.com/read/bleach/0/339/12, then i don't think it's water... if i'm to be personally honest it looks like it could be ectoplasm lol but i doubt its that... juries still out for me, but i dont think it's water. It certainly better not be.
I believe the "dai" prefix is from the original raw of the chapter in which they call her sempai, -106 or something, best ask Arwen really.
Well, she could have joined the gotei 12 at a very young age and been promoted quickly, whereas he could have been living in rukongai for ages and was already a middle aged (late 40's to early 60's) man by the time he joined the Gotei 13. So i guess what im saying is not that she's "older" than him as such, but has possibly been in the gotei 13 for longer, and as such is potentially viable as an "older" captain.