Questions about IUD's?

So my fiance and I have had 2 unplanned pregnancies. He was told he could never have kids hence our 1st. The 2nd was another oops oh sh!t, but not a mistake. To prevent another unplanned, pregnancy we have decided on me getting an IUD. The options we have are either him getting snipped or me getting an IUD. I feel that we may want another child down the road, and if in 5 or so years we both decide we don't want anymore he will go get a vasectomy. Ok, so now on to the questions. Does it hurt when they put it in? I will be having it put in at my 6 week postpartum checkup. Have any of you had any complications from the IUD itself? Do I have to routinely check to make sure it's still there? Can your partner feel it during ? Can you feel it? Are there other things I should be concerned about? Thanks in advance for your input!