Most Helpful Guy
Just know this: if he's single, and your friend, and is actively initiating interaction with you, chances are he's already interested. IMHO you should start cranking up the flirtyness to one hundred, then after a few days, if he responds well, ask "so... Where are we going? What are we?" Or something. Flirting tips: touch him lightly, kiss him on the cheek, and a big one graze your hand over his back, all the while talking in the sweetest voice you can. Just don't do it all together or he'll think you just want to have sex :)
Just know you already have a solid 70% chance.