In addition you can turn it off just by clicking again the mine button before closing your pc but if you are using VPS I think it can run 24/7 so there's no need of closing it but in case you have some errand to do and you need to close the computer you are using to mine you can close it so you will not get any penalty.
What are the requirements for the VPS? Does it have to be a server with powerful hardware or can I use a free VPS from Amazon?
No, you don't need a powerful VPS, since you are not doing real mining, you are just running a node. For example, I have a VPS with 1 CPU and 2GB RAM, and is running like a charm.
Any comment on bandwidth requirements with VPS?
Docker container uptime via top command: up 55 days, 22:02
Docker input / output via docker stats command: 654GB / 957GB
Now we can do the math. 55 days 22 hours = 1342 hours, 654+957= 1611 GB total traffic, 1611/1342= 1,2 GB per hour or = 28,8 GB per day.