Is this a good solution For multi sites

I would like to use it for a community network of sites that would share one Forum or buddypress but not necessarily have equal access to areas of forum.

The would be for a multible of site related to this one community for example:

A Freelance directory site

A house directory site

A how to make money on line site related to this community

A potential Word Prese site that can handle a particular yet to be created web app (i guess it is called) APP?

And more.

obviouls will be using a viriety of themes based on what is neede to make the site work.

If I use sometihing like genisis framwork for some of the site networks theme, can I go out side of that framewor for other themes that may better suit some sites?

Thanks for you help answering these questions as i try to wrap my brain around all of this will work. Thanks