Layne is the best.
#2. I had the same problem - just finished grad school and people routinely assume I'm 5-7 years younger than I really am. Whenever I wore a suit, I looked like a child playing at dress-up. I finally went to the Theory outlet to buy something that would fit properly and look grown-up. The salesman asked me all of these questions about buttons and cuts, etc, and overwhelmed, I panicked and said, "I just want people to take me seriously!" Done and done. He picked out something that is both adult and modern. My boyfriend didn't even recognize me when he saw me (which is slightly troublesome, but...).
Anyways, short answer: Ask the storepeople whose job is to help you!
Hi! Said burqa is actually an abaya, hijab, and niqab combo, but burqa just seemed easier for the email. The niqab part freaks me out as well. I would love to wear the rest of it if I were in a context abroad that called for it, but I'm not sure I could handle the face masking part.