Lpc2000

Hello,
      I am not really understand the function and capability of IAP.
Here are some questions could anyone help me to clarify it.

	1. In my opinion the IAP function is used to read/write
           flash memory. Thus,I can use my flash memory to store
           some data that I do not want to vanish after power down.
	   Is that right?

	2. IAP function can be use to upgrade the firmware.But
	   my question is why it will not erase itself?
	   Or how to avoid to erase itself? If I want to
	   upgrade the whole firmware.

	3. Can I use IAP function to upgrade whole firmware via
	   I2C,SPI or USB(if I have USB ability). 

Many many thanks to whom who care about this!!

Regards