1. You also want divorce and wanted to file MCD, so you have no problem in his filing the divorce petition. If he does not appear before the Court to attend the hearing of the case filed by him, then you file a separate divorce suit claiming damage, return of streedhan etc.,
2. In your 498A complaint you should have added the charge u/s406 of IPC alleging that he did not return your streedhan. Police would have collected your Streedhan for you,
3. If police has not taken any action, file a writ petition before the High Court against the police for its inaction praying for your relief,
4. Yes, you can produce screen shot of his linked in profile which will be treated as digital evidence acceptable by the Court.