Zenitoni dental clinic on gowabi has Zoom teeth whitening for about 3000B. Otherwise Crest 3D white strips give great results as an at home alternative, gave me better result than in clinic whitening.
there's copy shops on either side of the immigration office at IT square. Photos cost about 100B if I remember correctly and a couple baht per document photocopy.
why don't you post an actual source rather than oh I heard this just believe me... Like seriously was it that hard to copy and paste the source? I have no idea who you even are mate...
It's a ticket departing Thailand within allowed time period, so to Cambodia for instance is fine. You can get cheap onward tickets online for around $10 or just book a cheap ticket to Cambodia for $40.
It's normally airline staff that ask, very rarely immigration ask but it is a requirement and can be used to deny entry.
you'll need proof of leaving for the visa application. So if you book your flight from Bangkok (or wherever in Thailand) to Cambodia then that will meet the requirements for the visa application and keep airline staff happy. Bus ticket can sometimes be accepted but not always, so easier to just fly.
Plan seems fine. Maybe just book a flight from Thailand to Cambodia instead of a bus ticket within the first 60 days. It'll minimize potential issues with applying for 60 day visa and airport staff.
Most likely no issue, never really get checked flying in. You can post them as an alternative option, done it a few times from Australia without issue.