Proposed Marriage of NRI son and Resident Indian Daughter in Law

SON : Hindu, never married ,Indian Passport Hlder,Currently In Germany, He would be joining Technical University of Twente,Enscade ,Netherlands as Assistant professor w.e.f 1st February 2023, Apart from Passport and Residece Permit ( Temporary Residency already issued .Appointment fixed for Residence Permit ) ,he has Indian documents like ADHAR CARD, NRE & NRO bank accounts and Indian Passport Proposed Daughter in Law: Hindu,Never married ,Resident of Dumdum Nager Bazar,Kolkata, MBA by education,She has PAN CARD ,ADHAR CARD and Voter ID Q1 Is there requirement for Any other document for my son. Some suggest NO OBJECTION certificate from Indian Embassy, The Hegue,Netherlands. Is it true? Q2 Can the marriage be registerd under special marriage act, Q3 is it true that Law requires 30 days notice to be served to the Marriage officer duly signed by bride and bridegoom. Can my son sign the application (notice) while in Netherlands and would be daughter-in law shall sign the application in Kolkata and file it with all the necessary documents to marrige officer Q4 I am staying in Joka Kolkata . Parents of would be daugter in law is staying in Dumdum Nager Bazar,Kolkata. who will be Marriage Officer under Special Marriage Act 1954