port monitoring mechanism

It has to be store and forward, because the port being monitored might not be running at the same speed and duplex as the monitoring port.

I don't know, sorry. I can say that what I've read of the

2950 / 3550 / 3750 (and kin) would not allow the packets to accidently get reordered: in those switches, the packets are put on a shared bus with a bitmapped header indicating which ports should grab copies of the packets, and port monitoring is just done by setting the appropriate "take a copy" bit as the packet gets processed on to the bus. But other switches handle things differently; I wouldn't want to provide a definitive answer for crossing between line cards on something like a 6509.