In principle yes. It usually takes about 20 mins to do re-entry at Suvarnabhumi (and often enough just queuing at passport control takes longer than that) Though note the above about the mechanics of your connection

@Mathew ********

a nice level of pragmatism shown by the immigration office there ;)

Based on what you said I would wager you won't have any problems. Your stays are short and you haven't done extensions, so I wouldn't worry.

If you're in Bangkok it's much easier to do it at the airport I would say. Just allow an extra half an hour (though usually it's done in 5 minutes)

Well... if he's just coming for 2 weeks and leaving again, having no contact with immigration, no harm will come if you don't do it

1) Yes,

2) The only reason I think you could be refused is if your visa were expiring today or something like that. I'm not aware of other reasons, but I may be wrong. I have done it several times at DMK and BKK and always found it quick and easy (quicker and easier than a trip to Chaengwattana)

It's only enforced in a pretty limited way in Bangkok. There is no need to do it every time you re enter the country, for example

The answer to your question is in your entry history. If this is your first entry into Thailand, and your return from KL will be your second, it's overwhelmingly unlikely to cause a problem. If you have been multiple times and/or have a history of back to back stays and extensions, you may well have a problem. Either way, you'd be well advised to have the '3 proofs' (cash, accom, onward travel)

@Richard *********

For future reference, in the situation you describe they CANNOT force you to go back to Australia. It's legally a bit complicated, but in most cases it's the airline's responsibility to get you back to KL. Unless they legally deport you (which they did not as you were not in the country to begin with), Thai immigration has no right to determine where you go outside of Thailand.

You don't need to bother in BKK... You only travelled domestically. Bangkok doesn't enforce this at present when returning to your already registered home either domestically or internationally.