if i would like to instal linux from a drive disk
I don't remember seeing that option in RedHat 7.3
RedHat Linux is usually installed from CD-ROMs.
As for your last question.
No, RedHat still does not have the option to save the list of selected RPMs to floppy disk during the installation.
However, I believe that Mandrake has had that feature ever since the 8.0 release.