Backing up my iSeries with tape

Hi all,
 
I am looking to backup my new System i5 and want to purchase tapes.  With
the machine I received a "VXAtape X6 Test Cartridge 62 meters" but it says
not to use it for doing system restore type saves - so I guess I wont use it
period because it sounds like that tape might have some self-esteem issues
it is working through ;-)
 
Back in the day of me being an AS400 operator I remember rotating tapes so I
am guessing I will want to buy a pack of tapes for my internal 80GB VXA-2
TAPE DRIVE and do a backup every night (or so).
 
So here are some questions I have and would like to know how everybody else
in the iSeries world does it.
 
1. How/Where to buy tapes for 80GB VXA-2 TAPE DRIVE? (I can get 5 shipped
tapes for $315.50 at www.compsource.com - good deal?)
 
2. Frequency of backups? Every day of the week I would guess, or anytime
enough data could be lost that it would make it painful to have lost it.  I
plan on doing backups EOD every weekday and then a full system backup on
Fridays backup - good approach?
 
3. How long do you keep your tapes in rotation before quality of tape comes
into play - 1 year for each tape (equals 52 saves on each tape)?  Sure each
tape will come with a recommended usage, but I would like to know what
people are doing in reality.
 
4. What do people do for offsite backup?  I have heard of taking it to a
sister company or another facility (which I have 70 miles away), or doing a
safety deposit box at the bank.
 
Anything else I am forgetting about concerning tape backups?  Any other best
practices?
 
Thanks,
Aaron Bartell
http://mowyourlawn.com