traffic can go through the CSS, but the destination ip should not be a vip but the real server.
In your example 1, if you want EXCH-A to contact FAX-A, I think the easiest is to open the connection directly with FAX-A and not a VIP and then ask the CSS to identify somehow that the connection should go to FAX-A.
So, keep it simple.
FAX-a can open a connection to a VIP, which is loadbalanced to one of the exch server, and this one simple open a connection directly to FAX-A.
Same for question 2, if the destination must be KER-A, I don't see why you would want to open a connection to the VIP.
If really it was required to contact the VIP, I don't see what the CSS could do to find out the traffic must be sent to KER-A or KER-B.
For HTTP traffic, we could look for cookie or portion of the url, but for other protocols there is nothing available.
Gilles.