What exactly do the yo-yo accessories do?

Terraria 1.3 added yo-yos to the game (and they're pretty cool!). I'm a little confused as to how the corresponding accessories work, however. Specifically:

• What exactly do counterweights do? Do they alter the time the yo-yo stays active once thrown? What's the benefit of equipping one?
• There's an accessory allowing you to throw two yo-yos at once (I believe it's the yo-yo glove). How does this actually work? Do I need two physical yo-yos equipped in my hot bar? Or does this accessory allow me to throw a second instance of the same yo-yo I have equipped?

• The counterweights fire a second projectile, (the counterweight) after hitting an enemy with a Yoyo, it's like a mini-yoyo, but most of the time it's thrown in the opposite direction of the yoyo- itself. Specifically it will travel over your head, most of the time. With some quick testing they appear to deal about 70% damage of the yoyo.
• The Yoyo Glove allows one yoyo to be used twice per fire, so it will duplicate the Yoyo you are wielding when you attack a mob, making the duplicate Yoyo travel in a circle around the original Yoyo thrown.