There was a specific on/off assembly Booyah made. They are very hard to find. But luckily a AGD ULT on/off will work perfectly. So, I would suggest just using one of those. But make sure your valve can take a ULT. classics and some RT Pro/Retro valves are not able to handle ULT's. All xvalves can though. Enjoy your BooYaah, they rip and are lots of fun. I have two of them and they are fantastic!
Not sure on how to find a manual, but by just going through the buttons you should figure out all the settings pretty easy.