Sorry don't use the server version, but perhaps I can through some light on _avast4_ and Webshlock.txt.
The _avast4_ is where avast unpacks archives and scans temporary files, the file names normally start with unp999999.tmp (the 99999 being a numeric value) and isn't the original file, though that would be locked whilst scanning completes. The file would be released and the unp99999.tmp file cleared if no detection found.
So it is normal to have no files other than the Webshlock.txt file if there is no scan in progress. The Webshlock.txt file is used by the Web Shield so wouldn't have any impact on local system files.