Virtually all resident AVs insert hooks of some sort so that they can intercept items/traffic in order to scan it before it is actioned.

Running specialist tools like roguekiller are more than likely to throw up things that look strange, which is why generally they are run under the guidance of a malware removal specialist. Otherwise it can cause more confusion rather than clarity.

Personally I think you should do a clean install of avast 9.0.2006, uninstall avast 8 using control panel > programs and features, then use aswclear.exe to ensure clean up reboot and only then install avast 9.0.2006. That will give you a clean start with none of the references to old avast installation locations in the registry, etc.

I can’t help on locking down svchost, as it has a legitimate use in windows updates and would probably require a complex rule in your firewall, which I don’t know what that is. I suggest that you modify your forum profile and compile a signature giving some information on your system, so when seeking help people don’t have to ask these kind of questions every time.

Since ivp4 is being upgraded to ivp6 (running out of ivp4 IP addresses) and many domains now have an ivp6 IP address then I would say yes you need it.