You can work as per the limits and conditions applied to your current work permit until you get SOWP.
When your current study permit and work permit expire, you will be on maintained status from your application for SOWP.
IRCC is quite lenient towards unauthorized work and overstays within spousal sponsorship applications and it doesn't trigger significant issues, there's a public policy covering that.
Attempt to make a case look stronger is of the most common red flags.
Why should you if you are married and so on. You need to provide information you are asked for, no more no less.
Procedural Fairness Letter is highly unlikely but more scrutiny is for sure.
Why would you provide engagement date for spousal application in the first place?
1. Nobody can tell but use FV – In Canada – Humanitarian and compassionate considerations
2. Usually very quick.
3. None, but you can have a survival job, nobody will punish you for that.