Hi ALL

I Want to design a project with ISP Chip.
I Want to know, what kind of considerations do I Need
To think about when I use it, and have some questions:

1) when I Program it, I Need a supplies, how do I Make sure
that the entier circuit will not work at the
programming process?
2) How can I use all the PORT Pins, If those are used to
program the CHIP ?
3) Do I Need to change the CRYSTAL for programming ?
Thanx
Oren