I did it in November I think there are about 12 questions where you need to upload proof. Most are quite straight forward but a few are confusing. I sent an email to the embassy and they just said upload what you think is most relevant.
The hotel should have issued you a statement that you had completed you sha stay. I have to renew mine next month guess I will have to hunt it down I didn't know this would be required to extend the stv
The covid extension was meant for people who could not return home. It's not a free pass for someone who wants to stay longer. At the moment they are turning a blind eye but you never know when they will stop this.
One option I believe is now possible is a flight to cambodia