penn reels and their drags

[Lord of the Rays]

hey,

at the moment my largest reels - a penn senator 6/0, longbeach 268widespool, they both fit about 500mteres of 24kg/55lb berkley big game mono.

i have several questions about penn reels.

-how does the 6/0, 9/0, 12/0 thing work? what is that nuber relative to?

i want to get a larger reel, im thinking 12/0 or so, so that i can run lots of of 24 or 37kg.

im looking at using berkley mono, 37kg, and i would like to get a reel i can just unload basically 1200mtrs of 37kg/.94mm line onto. is there a formula out there i can use to work out how this is going to work
24kg GREEN 1200MTRS 24kg/.68mm
37kg GREEN 1200MTRS 37kg/.94mm
60kg GREEN 1200MTRS 60kg/1.25mm

i am really fond of this sort of line because of its knot durability, i get about 90-95% knot strength with a double palomar knot on a normal large swivel. although it does stretch a bit i have been around the block with monos and i find it to be the best.

a 12/0 is really as far as my budget will go, not to mention getting a decent rod. i figure if i can fit the better part of 1000metres/1100yrds of 37kg/85lb on a 12/0 ill be happy with that. i dont really want to higher than 37kg/85lb.

also, how do the drag strengths vary throughout the reel range?

thoughts?