yes http://www.google.no/search?hl=no&defl=en&q=define:Microsoft+Silverlight&sa=X&ei=9ZVsTbPnKcaaOoHr2YAD&ved=0CBkQkAE
avast + MBAM pro
not necesarry
avast + MBAMpro + SASfree
OK
good, very few FP…but never install more then one AV if you do it can create all kind of mysterious windows errors and false positive detections
see 2 and 4
MSE works on XP also