Buyer will have to pay custom tax (if any) for their country. Make sure you stress this point to the buyer to avoid any surprises. Each country has their own import rules. Your job is to declare the item and the value properly.
Insurance is optional, not by default. Without insurance, courier company will only pay up to a certain amount (Pos Laju is RM100 IIANM). If you think you do not want to bear the risk, buy insurance.

You can find more info about Pos Laju insurance here: http://www.poslaju.com.my/services/

General Post Office aka Pejabat Pos Besar. The biggest post office that you can find in Johor Bahru.