Part-time jobs that fit around childcare (update)

A grocery chain and a hotel near Kansas City are hiring part-time staff. I have read a lot of threads here and could not find my exact situation. Shifts are four to six hours and the pay is weekly. How many hours do they guarantee?

Thanks for writing this out. I went through something close to it 6 months ago, and it got easier once I kept a simple log of every call and form.