Documentation can be found on www.aircrack-ng.org
See also manpages.

Madwifi-ng known bugs:
When changing rate while you are capturing packet makes airodump stall
  Solution: restart airodump-ng or change rate before starting it

You can use airodump-ng on OpenWrt devices. You'll have to use specify
prism0 as interface. Airodump-ng will automatically create it.
Rq: Aireplay doesn't work on OpenWrt with broadcom chipset since the driver doesn't support injection