(2) What are his moral / emotional weak spots?
Celestio is a perfectionist, and a control freak. He always feels the need to do things exactly right, or else not do them at all. He is very easily distressed and flustered when he feels like he's losing control of a situation, such as when something unexpected happens that he wasn't able to prepare for beforehand. He especially hates the idea of himself being controlled or manipulated by someone else.
(7) What are his tickle spots...?
What a weird question... Definitely not something I've thought about. I'd say Celestio is actually really ticklish, the sort who feels tickled even when you haven't even touched him yet. Aside from the obvious tickle spots, he's got some really weird ones too, like on the upper arms or the small of the back!
(13) What gets him flustered?
Like in by answer to (2), Celestio is easily flustered when he's in a situation he feels like he's losing control of. For example, if something he meticulously planned with several back-up plans is rapidly going downhill despite his preparation. In addition to that, he'll be flustered when someone flirts with him or makes inappropriate jokes. He just hasn't really encountered a lot of that kind of talk in his life, and doesn't know how to respond to it.
(17) What are his regrets?
He feels like he has spent too much time and effort worrying about what other people think of him. He grew up being really self conscious, and always trying to control how he presented himself so that people would perceive him in a certain way. Now, he's kind of realized that the opinions of some people shouldn't really matter, especially when they're people you don't even like or care about.
(22) Who are the people who have influenced him greatly?
First and foremost is probably his Creator, Theodor. He is probably the one person Celestio looks up to the most. Theodor is not only his Creator, but also his Mentor. He got from Theodor his thirst for knowledge, his desire for greatness, and of course his ultimate purpose. He doesn't love Theodor as one might love a parent, but he deeply admires him, and hopes bring honor to his Legacy.
The second would probably be Lady Elena, Theodor's mother and the woman who raised him. She's a terrifying woman-- quick-witted, sharp-tongued, and often ruthless. Celestio does not think fondly of Elena, but he did learn a lot from her. He learned the arts of deception and subterfuge. He learned diligence, prudence, and responsibility from her. Of course, he picked up a lot of negative things from her as well-- misanthropy, distrust, and perfectionism.