If you fly Business, you are entitled to everything you said. If you fly Economy:
a. You can check in at Krisflyer Gold Check-in counters. If these are not available, then Business Class counters. These Gold counters normally exist in Singapore terminals.
b. You can use Krisflyer Gold lounges. If these are not available, you can use Silver Kris lounges.
c. You are entitled to priority boarding.
http://www.virgin-atlantic.com/en/gb...fits/index.jsp

From 2009, both SQ and VS Gold card holders are only allowed to use the flight operator's lounge. e.g. if you are a VS card holder flying LHR-SIN, you can only use SQ lounge at LHR.