You can download all software from the official TeamSpeak website.
You can edit the general settings of your server such as changing the banner or the server password via the following steps:
1) Click on the server name with the right mouse button.
2) Go to "Edit Virtual Server".
In the TeamSpeak 3 Client go to Preferences -> Application -> Check Advanced Permission System.
Yes, you can also use the mobile client to connect to your server.