I'm not sure the gist of your question, but might be able to give some info. Are you trying to decide to use Symantec vs some other software?I used to recommend Symantec several years ago. However,...
Yup. In the general sense of the term "virus" (any malware that can be installed on a computer), there are some kinds of malware, usually called downloaders, which can actually download more malware...
Use a good antivirus to know if you have a virus. Examples are: Avira uit Duitsland avast! uit Tsjechiƫ BitDefender uit Roemeniƫ Computer Associates uit de VS ClamAV - GPL ClamWin - GPL ClamAV voor...