Basic Backup Strategy Advice

[Gusto5]

I'm trying to get some basic info on backing up my G5.
I know there are a great number of bells and whistles in SuperDuper but I'm looking to establish a basic strategy.

My goal is to simply to have a bootable backup HD and to backup my media (photos/video/audio/documents/files).

I have two internal hard drives (for the purpose of this discussion I'll call them A & B) and one large external HD which has been partitioned to mirror the two internal HDs (AA & BB):

Internal HDs
A G5 OS HD
B G5 Media HD

External HD (partitioned)
AA G5 Bkup OS HD
BB G5 Bkup Media HD

For my A HD when I want to do a backup I assume I should use the following settings:
COPY Select: A G5 Boot HD to AA G5 Bkup OS HD
USING Backup - all files
DURING COPY Copy Different Files

For my B HD I assume I should use the following settings:
COPY Select: B G5 Media HD to BB G5 Bkup Media HD
USING Backup - user files
DURING COPY Copy Different Files

Questions:

1) Does this setup look OK - or what problems could this setup create?

2) If I added some additional media to my backup BB G5 Bkup Media HD , will using the setting "Backup - user files" and "Copy Different Files" create a problem for me - or will this setting ignore the added new media and basically check the B G5 Media HD against the BB G5 Bkup Media HD and only copy what's different from the original B G5 Media HD to the BB G5 Bkup Media HD - and leave the new media alone?

3) Are there other procedures besides "Schedule Backup" that you would suggest I add for my basic backup goal?

4) One other concern I have is, I tend to try and keep stuff (media/files etc) much longer than I should - can't stand throwing stuff away. Using the above setup my BB G5 Bkup Media HD will continue to fill up until I can't put any more in.
I could just buy another HD and keep going but if I decide to go into my B G5 Bkup Media HD at some point and trash stuff (media/files) what setting would I use to make the BB G5 Bkup Media HD resemble the cleaned up B G5 Bkup Media HD?

Thanks in advance for your help.

Gus