As far as I'm aware the PAIR system does not connect directly to the tank but has connections from the airbox and on the carbs that lead to the little pair device thing then has hoses that lead to the reed valve things on top of the cam covers. You see the oblong blanc's on top of ours where they would go.Don't forget that the american bikes have the PAR system
Yes there is that one which is the overflow, but there is also the breather pipe. You have two pipes that connect on the base of the tank.The only vent tube I'm aware of is on the outer rim of the fuel filler
It looks that way so don't lean too farAlso, if there is some vent line high up in the tank

I'm gonna see exactly what's going on inside these tanks soon and how everything routes for sure. I have a spare I want to cut the base off and extend the tank to make bigger. I might just bring that little project forward.

(:-})