Seven days only, then pay then 1,000 baht overstay on the way out. Payment at CNX is easy, you pay it on the left just as you pass international security and there are zero hassles. You could of course just overstay 9 days but it would be cheaper to get the 7 day extension then pay the 2 day overstay.

Tip - if you dont want to share your passport number you need to cover up all three instances. Also make sure you've got at least 6 months validity left. Im pretty sure M series passports were phased out in 2009.

It's a virus that keeps on spreading :)

4x6 with a blue background. If you don't have them the copy shop next to immigration can do them for you.

Chulia Mansion is brilliant and right near Jim's Place so you can use him to do it for you. If you absolutely want to do it yourself, book a Grab car, it's not a costly ride.

Yes, it's a 500 baht per day fine for an overstay. You'll pay it on the Thai side and get a small stamp in your passport for good measure. There shouldn't be any dramas when you get to the crossing. Technically if you're caught on the way to the border on an overstay you could be detained, but it's highly unlikely one day late - if asked, tell them you're heading to the border.

YESSSSSSSSSSSSSS :)

The very short version is you won't be catching your flight as you lack your passport. I'd be looking at changing your flight urgently or if you can't - book a new one.

Legally no but it is up to the landlord. Standard is a two month security deposit with the first month rent when you sign the contract.

Maybe ask an Australian FB group - this group is for Thai visas.