Hi nivm,
If you happen to be using Javascript, you can get our Javascript driver from GitHub or NPM which will give you functions to do all of those. There's a driver for Go as well, but we're currently working on moving it into its own repository separate from the rest of our code base.
If you aren't using either of those or would prefer to make your own, those APIs are available with:
1. a GET request to /api/v3/teams/TEAMID/channels
2. a POST request to /api/v3/users/status with a json formatted list of user IDs that you want the statuses for
3 a POST request to /api/v3/teams/TEAMID/channels/create with a json formatted channel object