Simple Multisite Questions

Hello everyone. I'm new here and this is my very first post. So please forgive me if these questions seems basic and probably redundant to most of you here.

Ive' been given the responsibility of creating a multisite/buddypress website. Its about a weight lost vitamin product. The owner wants me to enable a network of mini blogs about this product that each and everyone of the users can write personal information, load pictures and link it to their Facebook page. He wants something similar to Ning. But I told him that Ning has limitations and that multisite is accessible to the Internet audience, which allows him to create leads. With Ning you have to create a login, which is a hassle and most people don't want to go through with it just to read a posting.

Therefore, my question would be can each user of the multisite personalize their own page and can link it to their own facebook page? If so, how?

When they join the multisite network, can I set it up so that there would be a announcement on the main site where so and so just joined? Like a personalized welcome to whoever just joined.

Next, when users create their own post as testimonials, is there a plugin that can index their postings? If so what is it?

And last of all, can multisite create groups like Ning? And would each user be able to select the group that they want to join and do group discussions, etc.

Thanks so much for your help.

Hope to hear from you all soon!