Agree on all these points. Your dad should be fine, especially if he’s supervised (but note DT official stance is get a pro if possible, but you’ve made it clear it’s not really so), my recommendation is get very comfortable with all the videos provided. I splurged for the surgical marker on my first one, it’s good to triple check your location when you’re new to doing it. Learn sterile field technique, because the last thing you want is an infection. Seriously. Get sterile gloves if you can (I found all this gear on eBay, but your physician friend may be able to source). Sanitise your surfaces, the glove package can be a good field above your sanitised surface.
I’ve done this a few times, and it’s been easier each time. The first time I bled everywhere, wore a bandage for a week, and it was rather achy in the spot for a while. The second (a LF tag into the same spot as my first, a xNT) was quicker, easier and I did it on the kitchen table. The third, my xG3, was done myself because my assistants ran off to chuck, and was a 5 minute job (courtesy of pain numb cream).