Hi Werner.
The best info I have come across in the UK is via the owner of the web-site
www.koi-unleashed.co.uk His name is Duncan Griffiths and he is a part of the AKCA KHA group, which is where he gets his info from. His site is worth a look, but you've probably got the same somewhere in the States.
The answer to your pt 1 will be there I'm sure.
Pt 2. I have been told that the virus cannot live without a host for 12?-15?-18? hours. So if I had the problem I'd leave if for as long as I could, lets say a minimum of 48hrs. If you steralize, what do you steralise with. I've been told Iodine type treatments for nets etc.
3. There is no link so far between any of the aquatic viruses, carp, trout, salmon etc and any other creature. They all tend to be species-specific.
Close physical contact is suspected, with mucous transfer the focus, but it still needs to be proven. I know I have read that fathead minnows were eliminated from being carriers of a trout virus, I know I have read (very recently) that goldfish cant carry KHV.
rgds BERN