Under typical scenarios, a network switch needs to handle broadcast, multicast and unicast messages at the same time.

I'd like to understand

On a typical managed switch (1Gb Ethernet/10Gb Ethernet), 

a) how are broadcast/multicast/unicast messages handled differently?

b) what is the bandwidth and latency of handling broadcast/multicast/unicast messages?

c) how does load of different type of messages affect each other?

d) Why switching from broadcast to multicast will (or is likely, if done correct) reduce the load on switch?