I posted a video on Monsoon, but it's not part of the update. Community maps are now possible, and that version of Monsoon was taken from lvlworld. Most Q3 maps work, even if they require a bit of tweaking.
I'm fairly sure you can do that in the public build of QL ever since they turned PK3 encryption off, but only in practice games because the servers only run official maps. By giving us community servers they're opening it all up. It will be workshop integrated, but I'm not sure of the exact details yet.
Yes but ever since they stopped using encrypted PK3s you can just plop new ones into your base folder and the game will run them. I should have been clearer. I have fond memories of raztrainql_beta3 back in 2011-2012.
Either way the news here is that you can play them multiplayer.