A:AnswerIt should be set up automatically, if you are streaming through twitch and are used to the ps4 setup where the chat is shown on the right toolbar, the ps5 looks a little different. There is only a small chat display that actually fades away. Any time you get a new comment it should pop up wherever you've set it up. You might want to check your capture settings to make sure that the live chat overlay setting didnt accidentally get shut off.
A:AnswerYes you can...but the dualsense controller has a mic as well, and you'd prob. be better off using that mic...or one from from a compatible headset.
A:AnswerYou can record the gameplay and (I’m assuming the video in capture options), then export it to a usb drive and upload it. You can also sync your YouTube account with it and post directly to there