Only if you like to eat Western food, drink much alcohol and smoke cigarettes all day long.
Otherwise not expensive.
Taxi is cheap and high class.
Asian food is relatively cheap.
A lot of fruits and seafood.
I lived and worked in Singapore in 2006-2007.
The so-called "Pink ID" is useless. It is probably useful for foreign criminals who don't want to show their expired passport if stopped on the street by Immigration Police. but in most cases they will ask for your passport anyway!
You will receive a notice from the Customs in your mailbox. You will pay the tax online, you don't need to visit the customs office under normal circumstances. After you have paid the tax, Thailand Post will deliver the package to your home.
European Union introduced the same system 2 years ago for all goods from outside EU sent by post.
EU VAT is 20% on the average.
Thailand VAT is only 7%