- What are the default passwords for user 'root' and the Web UI administrator 'admin'?
The default password for 'root' (CLI) and 'admin' (WebGUI) is 'openmediavault'.
- The installer is asking me to plug a USB stick with firmware files on it for my hardware, e.g. NIC. Where can I download them?
- How do I reset the Web UI administrator password if I forget it and can't login anymore?
Use the omv-firstaid command line tool in command line interface (CLI), see section How to change admin password in CLI.
- How do I use the OMV webserver to serve my own content?
There is currently no support for this feature in the web interface. You need to connect via SSH to your server (SSH needs to be enabled). Also see the forum: 
Then you execute the following commands in order to create the directory "web" to store your content:
cd /var/www/openmediavault sudo mkdir web cd web
After this you can either add the content directly or upload files via scp.
nano index.php ###Add your content### ctrl + O ctrl + X ctrl + D (logout)
You can now access this folder by appending the name of the new folder "web" to the IP address of the server.