Inland Spousal + Might be out of status

Scenario:
+ Lived in Canada legally for more than 3 years as student. Working under Practical training for 6 months, work permit expired 3 months ago. Just received news from my employer that the work permit application was either not processed or denied. I am not looking to continue this route.
+ Been living with my partner for more than 10 months so far, we do want to get marry soon.
+ My brother did put me in his family sponsorship application (with my mom, waited for 2 1/2 years so far, he does have client ID).

Now, I would appreciate if someone can show some lights on either of the following based on ur knowledge and past expericences....
1. Am I technically out of status?
2. If I do want to go with inland spousal sponsorship, is it better to do common law or spouse (assuming we get marry now)? Meaning which case is stronger?
3. Could I apply spouse sponsorship together with my brother application which is in process now?
4. Timeline I could be looking at, doing inland with the complications of this case?

Again, appreciate it.