> + it has dowloaded some PDFs like risksuite.pdf, which is 
> not valid PDF.

Any errors in hts-log.txt ? The server may have sent this 
pdf as "text/plain" or something

> Looks like Set Options / Limits / Max connections per 
> seconds is GLOBAL PARAMETER
> It should be Global per domain

Yes, this is right - and this will be probably implemented 
in a future release (as the number of connection/sites)