To set mouselook to always on, add +mlook to autoexec.cfg.
Using existing joystick support, it is possible to add support for XInput-based controllers.
A list of configurations for the devices can be found in the Files section.
It will not add triggers support for XInput-based controllers as Quake treats them as axes and won't allow to map them. As a workaround, an XInput-to-DirectInput wrapper can be used, such as XInput Plus (actual tool is in English).
connect <server address or ip>