I can only provide pointers on 5 and 6.
for 5 there is another place the email is defined. it is the web-client-config.xml file in the actual alfresco webapp. Though, the custom file should over ride it.
if this fixes it you probably want to zip the alfresco webapp folder and rename it alfresco.war (no .zip) and overwrite the original alfresco.war file. This way you never have to change it again
for share point you need two things.
1.) install the VTI amp. In the root alfresco folder look to see if the vti amp is in the amp folder. if it is run the amp install script in the root alfresco directory. This script requires some user confirmations
2.) make sure the ROOT webapp deploys. It doesn't always deploy
vista hates webdav and i believe sharepoint is an extension of webdav. basically it looks like M$ screwed up their entire webdav implementation in all versions of windows at some point