If we buy a 10-trip metro/bus ticket, can my husband and me both use tickets from it? Or do we have to use separate tickets?

Thanks.

Yes, 2 people can use it and that is a GREAT idea!

You can both use it. (I do this with my kids). In the metro, the first person goes through the turnstile, hands the ticket back to the second person, who then sticks the ticket through the turnstile again. No problem.