dont worry hkbasi, they are trying hard to waive your interview
first review means they are investigating about your relationship.
ppr is the first step of NDVO (they just request passport and keep your passport with your application to avoid any delay when your visa is ready). after receiving your full application package from mississauga, VO goes through all of your forms and supporting docs, if they have any doubts about relationship or your intention of going to Canada, they request additional docs or schedule interview. if they are convinced with your relationship and your intention of immigrating to Canada, they send your information to some other agencies for background and security checks and update your ECAS to "in process". after receiving your background and security reports, they go for final review and issue visa.
hope it helps