Do Skyrim script has some sort of API? like what kind of variable/function exist that I can use.

Examples are http://www.gamesas.com/topic/1407995-script-possible-to-duplicate-items-via-script/page__p__21481611__hl__enchant__fromsearch__1#entry21481611 i see a lot of them like ForceRefTo, getEquipedWeapon...etc

I will like to know where I can read list of those.

The main functions I am currently looking at:
* Delete Object Reference
* Duplicate instance of object reference (Make a new copy)
* Access objects inside containers.

thanks in advance

This might be what you are after

http://www.creationkit.com/Category:Scripting

thanks. This looks like it