Hi.. see my responses below. Suggest you do a thorough research and post a thread in this forum to get other views as well.
1. Do you know which is the most common document they ask for ? or its case to case basis.
I have no idea since I wasn't asked any. They may not ask anything but if you feel there was a weak area in your application, be ready. Most likely ties with Ontario causes problems. Fingers crossed that this doesn't apply in your case.
2. Once they start the assessment of the application ,will i be getting any mail or I need to keep checking the portal for the progress ?
You will get email only when they issue nomination. Until then keep checking the portal.
3. How much time typically PCC takes to be done from India in your experience ? Should the address on PCC needs to be matching with Passport(no one stays there) or can I provide adhaar card address which is the place my parents are staying. ?
I recently applied for my India PCC and according to BLS, processing time is 4-6 weeks. It depends on police clearance from India for which we can't do anything. Re. your address, suggest you speak with BLS. They will suggest the best option. For a fast process, PCC address needs to exactly match with passport and there shouldn't be any existing criminal record. Check the PCC form filling instructions available on BLS website (https://www.blsindia-canada.com/toronto-jurisdiction/police-clearance-certificate.php). Somewhere there is also a sample filled form available.
4. Someone talks about the birth certificate also to submit, I dont have any and I came to know BLS provides it, not sure if again how much time it will take and should I wait for nomination before proceeding for the same ?
Yes, you need to submit birth certificates for all family members. Suggest you apply for birth certificate now as it will be required in any case.
5. I have a Notarised Marriage affidavit(which is provided for WP also and it worked) from India and no Marriage certificate, will it work here ?
No idea. Only IRCC can tell. You can submit this and in the meantime, arrange one from India if required..
Hope this helps. Please do get other views as I am not an expert.