saving when boot from cdrom (Linux)
 

If I run Linux from BOOTABLE cdrom or usb flash drive then:
may save files to HDD ? Programs(apps) installed and run on Memory RAM even in usb flash drive ? May install apps in usb flash drive and run later times ?
saving files:
when boot from cdrom may save to hdd ?
when boot from cdrom may save to flash memory drive usb ?
when boot from usb flash drive may save to hdd ?
when boot from usb flash drive may save to usb flash drive ?
when boot from usb flash drive may save to / burn a cdr/rw-dvdr/rw ?

You can save to whatever you have (A)mounted and (B) permissions to write to, no matter what you boot from.

USB FLASH DRIVES that come with preinstalled Linux, the Linux apps,data and actual OS are all secure or I may accidentally delete anything ?
may install additional Apps alone to usb flash drive for running an other time(boot from usb flash drive) ?
When you say "(A)mounted" you mean only files of this OS(Linux) installed in this drive, and also this drive specially configured ?
USB Flash memory drives (no preinstalled) , how can configured to accept Linux Data ?

Puppy linux is a live cd that allows you to save your session data to a USB drive.
http://www.puppylinux.org/

answer and rest of questions.... also on a Mac may boot from cdrom or usb flash drive Linux ? yes / no