Before I post my question I'd like to say I search too much in the internet and didn't find any answer or similar thread to my question... by the way

abcminiuser for AVRFREAK make a great AVR programming guide,

http://www.avrfreaks.net/forum/tut-hard-avr-programming-methods

I'd like to ask you some question about ARM from ATMEL like SAM3X8E one which used in Arduino Due

Q1/why there is no ICSP pins in Arduino Due to use it to programming the sam3x8e from external programmer instead of USB port in Due board?

Q2/If I want to programming Arduino Due from external programmer which one of these programmer in abcminiuser guide that do the job and give me the ability to programming AVR 8,16,32 bit and ARM chips from ATMEL in the same time?

Q3/ in Arduino Due website page I read this

"Uploading sketches to the SAM3X is different than the AVR microcontrollers found in other Arduino boards because the flash memory needs to be erased before being re-programmed. Upload to the chip is managed by ROM on the SAM3X, which is run only when the chip's flash memory is empty. "

What is that mean?

Thanks for everyone shearing his knowledge in this site,