1. I submitted copy of the police certificate with the application
2. copy paste the photos in a word documents and write the details beneath the photo. i put one photo per page and wrote details: what event, which date, who is in the pictures, what is their relation to me or spouse. i grouped the pictures according to events and i explained each event and what it was/meant like mehendi, nikkah, rukhsati, valima etc.
3. i believe they refer to this as the nikkahnama or the nadra marriage registration certificate. submit BOTH. if nikkahnama is in URDU then make sure to submit a certified copy of and a certified english translation.
4. no need, my wife did not submit any.
5. letters/mail/email sent to each other, if any. any communication you had with your wife submit that, whatsapp/viber/sms chat screenshots from your phone (add to word document resize to fit 6 screenshots per page)
6. screenshots of Facebook posts about your wedding, comments from facebook friends on your wedding post etc. written letters from friends detailing they know you and your spouse got married, how they know you, if they attended wedding etc.
7. not essential. this is usually needed if you have a lawyer submitting your case.