Questions about "Steps in Securing Your Zen Cart™ Store"

Hi There

I'm following this article:
STEPS IN SECURING YOUR ZEN CART™ STORE
from the last security patch

and at this point:
Protect your "images" and other folders

File/Folder permissions settings

On Linux/Unix hosts, generally, permission-setting recommendations for basic security are:

• folders/directories: 755
• files: 644I found a lot of my images, from bmz_cache folder with: 666

and in my images folder I found images with: 777, others with 666 and just a few with 644

is that a problem? why my images have that permissions and don't 644?

do you know how I can setup this, in order to all images upload with 666?

I need change it all to 644? or is ok if I just leave my images like was uploaded?

thanks in advance...