not at all, these are great questions and I feel silly for not having the info on the page! to answer:
- you need one referee/GM to run the game. the book suggests 2-6 players for the mercenaries in addition to the ref but I've had plenty of fun doing 1 GM + 1 player and also am about to run a FIST mission with I think 18 players, so you can get funky with it
- average play time is 2-3 hours but some missions go longer if they're particularly large, difficult, or complex
- there is no solo mode but there are 80 pages of random tables for story beats, characters, items, locations, mission prompts etc. plus a table of "what happens next" results for partial success rolls. this stuff is provided to give the ref an easier time but could be very easily combined to play your own solo mode (also someone in the discord server is currently playtesting their own solo hack to be released soon)
hope this helps and thanks so much for checking out the game!!