Siniša is pronounced "SEEN-ee-sha". Listen here:
http://www.forvo.com/search/sinisa/hr/
No,
Doris came into use in the 1960s and was never popular, so it’s not seen as that dated. I’ve only met one in real life and she’s 24.
Just to note,
Dean is pronounced ‘DEH-ahn’. Listen here:
http://www.forvo.com/search/dean/hr/