How to use hardware decoder with KMPlayer

On multimedia world and would like to ask pros here about some basic questions:

-1) Is KMPlayer default to use own software decoder for video and audio, and user must configure the "External Video/Audio Decoders" option to enable hardware decoding?

2) What is the difference between "Add System Codec" and "Add External Codec"?

3) There are a lot of filters listed down at "Add System Codec", how to know which one is software or hardware filter?

4) ATi display card says it has hardware mpeg2 decoding capability, do i need to configure anything for it to 'work'?

5) The Creative X-Fi has hardware DDigital and DTS decoding capability, what do i need to do at "Internal Audio Decoders", "Output Mode" or "External Audio Decoders" to enable it?