The soft lining of the uterus sheds monthly. I suppose you could "scratch" it, but it would be the equivalent of the wind blowing at the tear film of your eye.
The inside of the uterus is a small space. The IUD fits inside relatively snugly. The IUD can't be moved by running, jumping jacks, ski jumping, or any other such activity.
The IUD belongs at the top of your uterus. That is its normal location. You will know if it is moving up into your uterus because your healthcare provider is seated between your knees inserting it.
That is not how an IUD works. What an IUD do is to stop an egg from attaching to the inside of the uterus. It had no effect on the sperm. But no, it shouldn't hurt.
No; the IUD does not make a hole in your uterus, nor does removal. It rests in the empty space in the uterus.
If the IUD is not in the uterus, it has likely fallen out.
What do you mean by "lower uterus"? Do you mean in the cervix? Or Vagina? In either case, health care professionals (and the Mirena and Paraguard manufacturers) recommend that you call for an appointment after ANY movement of the IUD because YES, you may get pregnant.
The IUD does not "float," but generally remains in place at the top of the uterus.
The IUD should be at the uterine fundus, the deepest part of the uterus. It is not located in the cervix unless it is being expelled.
An IUD can move slightly within the uterus, but that's not common. More worrisome is the potential for it to move partway or completely out of the uterus, which increases your risk of pregnancy. For this reason, you check the strings every month to make sure you can still feel them, and that they don't seem significantly longer.
IUD usage is strongly associated with the development of PID. Bacteria may be introduced to the uterus while the IUD is being inserted or may travel up the tail of the IUD from the cervix into the uterus.
Menstruation
The IUD will not cause abdominal tightness. The IUD is in the uterus, which is behind the pubic bone; it is not in the abdomen.