There are many kind of POE switches in the market.
(1) Which kind is for IP cameras & NVR?
(2) How many Watts of power is needed for a 8-port POE switch?
(3) How many Watts of power is needed for a 16-port POE switch?
(4) Is it better to have several smaller-port POE switches than one 24-port POE switch connected to one 24-port NVR?