Nope and nope:
LW doesn't scan the files. It just tells you if a file is susceptible to be infected by a virus because of it's nature (e.g. .exe files can very easily carry viruses so LW will warn you when click "Dld file")
Also, sharing in itself is not illegal. It's what you share that makes it illegal: music and videos and what have you that the copyright owner has prohibited unauthorised diffusion are illegal to share, but that also includes downloading them from someone else. So, before turning sharing off, take some time to think that if everyone turned sharing off then you wouldn't be able to dld files anymore. Sounds good?

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

"Raise your can of Beer on high
And seal your fate forever
Our best years have passed us by
The Golden Age Of Leather"
-Blue Öyster Cult-