1. it is the design flaw of IE 9 (of course avast does not want it to occupy the whole taskbar, eg. google chrome and firefox)
webrep also check for fake certificates, which is pretty important.
source:
http://www.avast.com/free-antivirus-download#tab3Quote: The version 7 WebRep browser plugins provide greater protection against phishing sites, including heuristics detection of new phishing sites. Also, we can now detect fake/planted SSL certificates, preventing man-in-the-middle attacks against https sites. Additionally, we have extended browser support to Apple™ Safari™.
i would recommend u not to disable it for cosmetic reasons but its up to u