Most probably they get a sore butt and nothing else.
no
No, to reach egg & fertilize, must be vaginal. If you do both, be careful.
No.
Only in America
YES
To make them pregnant.
No
No.
yes if not how else do you think you could get pregnant
No, you cannot get pregnant this way.
Usually if someone is referred to as 'up the duff' then they are pregnant.