I need to toss that out there right now, and know its said with love.
Chicos is a nice store, but the attitudes you're talking about are Bergdorf kind of people. And I say that because Chicos and Loft are where almost ALL of my over 35 friends shop for work clothes or business casual clothing.
I also think the customers that want someone to shop for them will naturally gravitate to the Manager, because she has 'dressed' them before. This is something you can reach for, not expect to do on Day 1.
I would give it a try. You aren't on unemployment that will stop if you get a job. You shouldn't turn down THIS job because of a job you MIGHT get in the future, so I would stop worrying about your 2nd part time job before you even accept this first one, yes? ; )
Is your gut telling you this is bad or is your guy happier sitting at home than possibly standing at Chicos? 10-15 hours a week could be 3 hour shifts, is that something your feet and your back could handle?