1. Does Google have a "broadcast mode"? Because I think it's vital. The problem with Facebook is that it only had a broadcast mode and not a "circles" mode. But does Google+ have only the Circles mode and not a broadcast one as well? All social networks need a broadcast mode (AND a circles mode).
2. Does it have a real time communication tool, such as Gtalk, or maybe another chat program that works across the entire network like Facebook chat. I think IM features are important for a social network, too. If it does, how does it work? Does a different chat appear in each Circle? Or do I see all at once? I'm not sure I'd like to see all at once. It's acceptable in the beginning, but what if you have 10 groups of ~20 people each? I think I'd prefer to just go into each Circle when I want to talk to that group, rather than see them all at once, and having them all see me when I'm online.
1 - Yes. You can share to specific circles, specific people, OR "Public" to everyone.
2 - Sort of. Through the "Huddle" functionality on the mobile client, you can do real-time group chats. But that might not be what you're referring to.
To add to this, there is also a "your circles" option, which generates a post that is not fully public, but does post to ALL of your circles. So, it's some where in between the two options mentioned in point one.
2. Does it have a real time communication tool, such as Gtalk, or maybe another chat program that works across the entire network like Facebook chat. I think IM features are important for a social network, too. If it does, how does it work? Does a different chat appear in each Circle? Or do I see all at once? I'm not sure I'd like to see all at once. It's acceptable in the beginning, but what if you have 10 groups of ~20 people each? I think I'd prefer to just go into each Circle when I want to talk to that group, rather than see them all at once, and having them all see me when I'm online.