Q1 - No, doesn't seem like. You can check if her biometrics is still valid here:
https://onlineservices-servicesenligne.cic.gc.ca/extapp/bioStatusQuery
Q2 - Background = Security + Criminality. Since you said both are passed, I believe it is complete. To be a 100% sure, you could call them again.
Q3 - Because it's about to expire soon.
Q4 - If you pass medical/security/etc. - It means both of you passed and not one person.
Did you give biometrics for work permit previously? I assume your spouse is Inland now?