Is Drupal Commons right for me?
I would recommend starting with Drupal Commons as a base. It comes with a lot of prebuilt configuration that's very nice, like the fb-style walls for groups and for users. You get all the standard things you mentioned except for forums, but that comes with Drupal core, or you could go for a more advanced solution. You can disable any features you don't want in a per group basis. Commons already comes with a nodes as profiles solutions, so you just need to add the fields you want to the profile node. For chats you will also need an additional module, there are several, maybe this will help get started.

To answer your question more directly, yes Drupal Commons is right for you. It will save you a lot of configuration time, and you can see some best practices in configuration from what they did. Remember to back up your db often and don't be afraid to modify everything to suit your needs, you will learn a lot that way. As long as you have a a backup you can always revert.