Hi @thecanadianmrs
Please promise yourself to always stay on top of your immigration process from now on, as it may be long and painful. It would have been a breeze back in 2015 compared to nowadays.
1. Can you renew your Canadian passport now? You should be able to do it without leaving the US -> https://www.canada.ca/en/immigration-refugees-citizenship/services/canadian-passports/renew-adult-passport/renew-us.html
You ARE a Canadian citizen, despite passport expiration. It's not an issue. Your old passport with visa MAY be returned to you if you request it (research it more, ask Canadian officials and your fellow Canadian friends)
2. You can always get a co-sponsor. Your husband will be a primary sponsor regardless.
3. If you're still married to the same person or different person for over 2 years at the time your I-485 is approved, you will get a 10 year green card. The time you lived out of status won't help with getting green card or naturalizing sooner.
Your unlawful presence will be forgiven if your spouse is a US citizen. Any unathorized work will be forgiven, but you need to be honest about it.
4. Do NOT leave the US anytime before you get green card in hand, otherwise you will get 10 year bar!
Also, you will be in big trouble if you ever said you were a US citizen to get a job or some other benefit. That WON'T be forgiven.
As for the timelines, you can check processing times on USCIS website, it can easily take over a year to get your case approved.
Good luck!