Here's a picture of my carb intake, it's rear facing, and yes it's a variator model where the motor pulls inwards at full throttle. (Which freaked me out the first time I saw it... Oh my God! The Engine's coming off it's mounts!)
As far as an Air Filter goes, I asked the guy at Claude's cycles and he says he has one for sale. I'm waiting for him to reply and tell me how much shipping costs will be.
Seems to be a common problem that these things fall off!