1. After static charges build up, it can move to a new ********. This is called 'a static discharge'. So a static discharge should happen to the balloon and your hair. The balloon is made of rubber, which is an insulator, and can let a charge pass through them, but not that easily. So it doesn't easily let a charge to pass through it, and I think maybe it can spread to other places, including dry air and any conductors around, which makes your hair lose that static charges.

2. My guess is that when you are 1/5R away from the center, you are closer to the center than when you are 1/3R away from the center, so the force you feel will be bigger.(I mean when the force is big enough for you to feel, and you are extra-sensitive to compare the two forces.)

A1. I think that's because once the charge is built up, it cannot move until you come in contact with something else. For example, after you rubbed your hair with the ballon, a charge on your hair has no place to go until you touch or come very close to something. Electric charge cannot move easily through air so the charge on your hair will exsists until you touch a thing that is made out of ****l. But, ballooon is made out of rubber, so it's insulator, a material that doesn't easily let a charge to pass through it. So I think that because the balloon is a insulator, it doesn't easily allow a charge to pass through so nothing happens at the second time.

A2. Well, of course I think if you are less away from the center, the less force you feel and you can move easily through other objects, I think.

Q1. It is because the charge is taken by the air particles after some time. The air particles will take the electrons from the charged material. Then the force will reduce.

Q2. I guess I will feel more force the first time. The closer to the center, the more force I will feel.