I seem to be doing pretty well as a Ranger/Fighter/Rogue, but my detailed knowledge of the rules system in this game is well..........zero ;)

What I really want to know is what an Attack Bonus of +22/+17/+12/+7 for my main weapon and +18/+13 for the offhand actually means??

That you have 4 attack with your main hand weapon with a bonus of +22/+17/+12/+7 respectively. First attack gets d20+22, second attack d20+17 etc.

and 2 attacks with your off-hand weapon with a bonus +18/+13.

Oh well, I suppose that explains why I can hack most things to pieces in fairly short order :D . I presume that also means that as I have the cleave feat as well then I get 7 chances to hit at a time??