Q10
How the fuck does the game define off hand, if ever?
Q11
More importantly, how are your number and type of attacks determined? Is it based on the weapon(s) you wield, or purely your BAB? Basically, what I'm asking is, if your BAB is +16 and you have a longsword, a dagger, armor spikes, and Improved Unarmed Strike, can you attack with a Longsword at +16, Dagger at +11, Armor Spikes at +6, and Unarmed Strike at +1?
Q12
If so, and you have a set number of attacks per round based on BAB and you can fill them however you like with your available weapons, what's to stop you from taking the whole TWF chain for some reason and holding a random dagger in one hand (to satisfy the "if you hold a second weapon in your off hand" line in the feat) and then using a longsword for all your attacks, changing your choice of "off hand" as necessary to make it legal?