1. Where do all these updates come from?
Updates are things that happened in your networks, both your own friend's network and all the teams that you are member off. If someone updated their profile or loaded new photos, you'll hear about it in the updates section.
2. Can I change which updates I see?
No, the application posts all changes in that update section. You can search for specific updates if you click the "View All" button.
3. But I don't want changes I make to be broadcasted, how can I limit that?
You can limit how many of the changes you make are broadcasted to other through updates by going to the Settings area. Click Settings in the right top of every page, choose "Privacy Settings". You can choose which activities you want to be broadcasted.