Clone, what does it do technically in an iRule?

I can't answer all your questions I'm afraid, as you note there's limited documentation available and nothing related to how statistics are recorded. I can though answer a couple (although there's no guarantee I'm right);

 

 

1) Why no requests? I assume this is because for a clone Pool (considering it's purpose) it's not recorded.

 

2) Why no IIS log entries? This is because your IIS server is dropping the traffic when it gets to the TCP stack. It's not destined for an IP address on that server so it's dropped. Note my earlier comment that only the L2/MAC destination address is modified.

 

 

I don't think Clone Pools are going to meet your requirements. Perhaps you can explain in full what they are and I can make some suggestions based on that?