Kelly Hu will be at the Emerald City Comic Con March 28-30th this year. We will find out in about a month what her schedule will be at the convention and whether she will be participating in any panels. She probably will, for her upcoming show called The 100, if nothing else.
If you have a question you'd like to ask her, post it here. We'll try to select a couple to have ready if the opportunity presents itself. We can't guarantee that it will happen, and at the moment we don't know if there will be any discussion or coverage of her work on Phineas and Ferb. Also, there's usually a limited amount of time for people to ask questions in a panel, so there might be more people wanting to ask questions than they have time for.
The best kind of questions to ask are general questions. Actors and staff like Dan and Swampy have to be careful about answering questions, especially if they are about the future, such as "Will Stacy and Coltrane get back together?" They may give a few hints, but in general, they have to keep their answers as general answers so they don't spoil things for us.