Firstly you will need to login to the unit , go to System -> Digital -> Channel type, then select the configuaration that supporst IP. An IP camera is then connected to this unit via it's RJ45 (lan port) using a network switch or POE switch.
What is the Maximum resolution of IP cameras the unit will support?
The maximum resolution currently supported by this unit is 5MP
Is this camera fixed-lens or varifocal? The web page describes it as "3.6mm Fixed Lens", but in the description tab I read "Lens: 2.8-12mm Varifocal".
This is a varifocal camera.
Price per pair or single?
TT-105a is sold as a pair, Price displayed will be for a pair.
How many HDDs can I have in the unit?
A maximum of two HDDs can be installed within the unit.