1. Is this game playable with a GM and a single player?
In theory yes, but I suggest looking for an appropiate adventure for that kind of dynamic, Liminal Horror adventures can be of help, or look for anything in the grand scope of OSR stuff.
2. If I got a community copy of this game, would you be okay with me showing the rules of this on a stream while reviewing it?
Yes! But only if you send me the link of the stream to watch it as well or at least the VOD of it!