One More (Hopefully Last) Fan Question

My Antec PSU has 2 Molex fan only connectors. I understand that the fans I
connect these to are thermally contolled in terms of fan speed based on the
internal temperature of the PSU. I was planning on attaching my two rear case
fans to them. What I am uncertain of is the 3 pin connector from the PSU that
is labeled as PSU Fan Monitor Connector. My understanding is that this can be
used to monitor the PSU fan speed.

1)Does this mean monitor the speed of the PSU fans that are internal to the PSU
or the fan speed of the fans that are connected to the FAN Only molex
connectors?

2)Does one need to use this 3 pin monitor...if you leave it unconnected will
the thermal control for the 2 case fans still work?

3) If you want to use it do you just plug it into any of the 3 pin fan headers
on the motherboard? I had thought that those 3 pin connectors actually supply
power to some types of case fans but maybe I am wrong and they are just
monitoring devices.

Thanks.

Howard