Saje

they don't need a love story just facts on how you meet and then in person meeting
more important they need letter of intent to marry fiancee here in the USA
As far as wet signature i will let others answer as things change all the time

You can scan birth ceritificate and translation
the police report is not due till the interview stage/  it does not have to be with the application
if you were never married,  there is nothing to prove

Scans are good. They should be translated before sending.