Yes to the first, and no to the second. I actually have a picture the writer had drawn for me by Meredies not long ago that you can check out!
As you can see, our tails tend to be shorter than the whole length of our bodies (mine is a bit longer than average). They aren’t prehensile, but they’re used for balance. They’re also used when swimming. For being primarily land dwellers, they let us move pretty quickly in the water!