Call your airline now and ask customer service for the "disabilities desk" (DL's term) or ombudsman or whatever term that particular airline uses for special needs pax and talk to them about seating, wheelchair access, getting your bag stowed and any other concern you might have. I'm not saying they'll be able to answer/help all your questions, but at least you'll better know where you stand. Also make sure your limitations are noted in your reservation so the FA's know this is a real medical problem and not just a "wants extra help for no reason" issue.

At the top of this forum is a "sticky" - permanent thread - with some of the codes airlines use for levels of need. You might want to look it over before you talk to the airline.

Do you have a handicapped parking placard? If so, having it with you can sometimes eliminate questions from those you need to deal with - like gate agents. My level of disability varies and it isn't visible, so I usually keep my parking placard in hand with my board pass and other assorted papers when asking to board early and when the airline staff see it, they usually are pretty helpful without me needing to answer a whole lot of questions.

If you encounter busybodies who aren't in a "need to know" situation: either ignore 'em or give a blank look and say "That's confidential" because you don't owe them anything!