Re: Index page modification????
1. A buddypress theme isn’t so different from a standard wordpress theme, it just has a few extras.
2. Not sure what you mean by this, you have to install bp on wpmu, you can’t install them seperately. Bp is a plugin for wpmu.
3. Once installed bp correctly on wpmu or just wp, you get profiles, activities, groups etc.
Do you really understand what wpmu is? Basically its standard wordpress, but allows you or your users to make multiple blogs on one wordpress install. Buddypress allows you to turn your main blog into a social community, by adding profile and frieding options and the earlier named options.