The quick-release plate is attached to the tripod screw on the camera. To do this, the quick-release plate is removed from the ball head. It has a small bracket on the underside, which is folded out and used to attach the quick-release plate to the camera by hand. I use various Canon cameras. I assume that it also works with Sony. I am not familiar with the Sirui tripod and therefore cannot say whether the head can be exchanged. I have mounted the ball head on a Cullmann tripod.

Yes, and so does every other ball head on the market with 3/8 inch thread.

Yes, and this is a top ball head! I am very satisfied with it! With kind regards