1x by a doctor, 2x by the nurses. I think typically nurses do the IUIs in my practice, depending on availability.
No ultrasound guidance during the IUI (though we did monitoring up to the date they triggered or detected a surge). I don't believe they generally need ultrasound guidance as it just has to go in the uterus (compare to IVF/FET where they sometimes have a very specific idea of where they want to place the embryo). They used a speculum to see everything and then inserted a tube through the cervix. I had three total and had a small amount of pain and a drop or two of spotting with only one (incidentally the lucky one that worked!).