I would of thought if you are living in the same place you don't need to inform them due to new lease . I am sure you will get someone with more knowledge to confirm 😁
yes I had to provide a rental contract and I just asked the landlord to put one year ( I don't think the length of contact matters is more about them confirming your address)
You also need copy of landlord ID and blue book.
I can send you information of the paperwork I needed but it varies from office to office .
Yes , I have done this . Hardest part is finding a bank that will open account for you to deposit the funds. I would start trying as soon as you can and best in a big city . Bangkok Bank seems to be the easiest. You might be asked for money for an insurance policy,but it's not needed . I got my account opened in Chiang Rai.
Once you have the account it's best to check with the immigration office you intend using for the documents required. They are not difficult to obtain , just a few hours working out the paperwork.
It should cost you 2000 baht to change to non O and 1900 baht 90 days later for the extension. 90 day reports also needed but they are free .