Depends where you are but generally speaking you can extend it when you have less than 30 days left on your visa. The extension will be added onto your visa expiry date.
You can do this at the local immigration office where you're at when you want to renew.
no, it was only extendable by the unable to travel due to covid extension. If that's not extended then you'd need to leave the country or convert to a different visa.
most people didn't think they would've extended it last month but they did. If you want me to guess, and that's all it is, then no I don't think it will be extended again but we're unlikely to know until a few days before or even on the day itself.