Questions about example sentences with, and the definition and usage of "Supposes"

A: If your mom says "you are supposed to go to bed at 10pm." Your mom is saying she expects you to go to bed at 10pm, probably because it's past 10pm already, or she thinks you need to be reminded. If you say "I suppose I'll go to bed." You may not want to go to bed, but you don't know of any better option.

A: 1. should, 2. would, 3. used to

A: 1 - is wrong
2 - is good but this would be better:
He's supposed TO COME HERE in the winter. shorter and easier.

A: perfect

A: She supposes he's having an affair with someone's wife.

A: "It's not doing what it's supposed to."
"It's not doing it how it's supposed to."