Video Live Streaming and Video Recording

For a security surveillance project, we need to create the following software: 1: Camera shall be installed in the office room. 2: The recording shall be stored in the hard drive at office premises. 3: There shall be an android app for supervisors wherein they will be able to directly see the office room view. Hence the live streaming of video should happen on android app. Additional features that are required: 1: User can access multiple camera videos live in his app. 2: Based on parameters the frame rate, resolution and mode [color, gray scale, black & white etc.] property of the video can be changed for live streaming of any user. For ex. 1) Below 10 users, frame rate shall be 30 and camera quality will be color. 2) Above 10 users, frame rate shall be 20 and camera quality will be black and white. So we can set all possible properties base on given criteria. - Admin user can see the high resolution live video streaming Some question based on this regarding hardware requirement: 1) Which DVR or NVR we should use for achieving this requirement? 2) Which compression technology we should use for this? 3) Which camera we should use for this? Candidate with prior experience with such work shall be given priority.