Flicking the tongue a lot is very normal when being held, they are exploring. Our older snake randomly stares at me in the face for long periods of time, it freaks me out sometimes so I just gently move him to the side haha, I don't think it really means anything.

If you are careful with the snake, I don't think you'll get bitten.

Be careful around shedding time, some snakes can be very grumpy.

Feeding in a cage doesn't usually create cage aggression, just don't hold them the day of feeding, and you know the rules for not holding them after.

Just make sure to look at the signs, if they seem more jumpy or freaked out than usual, give them some space. I don't think most well handled balls bite out of aggression, most likely it's out of fear.