(IM) Tapering...what tapering?

There are a wide variety of tapering methods.  Some people find certain methods work best for them.  Other people prefer, well, other methods.  There's no magic "perfect" taper for everybody.  All of the suggestions you list are feasible.  The only good advice for everybody is that it's better to be "too rested" than not rested enough.

As far as diet, I say just eat normal.  But remember you're training less so eat appropriate portions.

You know what. I don't know if it was nerves or something, but during my Timberman taper, I tried to keep my eating exactly the same as usual...eat at my usual times, similar snacks and meals (in size and type), and I was ABSOLUTELY STARVING. Actually, I was getting a little worried about the race, because starting 5 days out, I woke up very hungry every morning. I was even waking up and eating in the middle of the night, because I was so hungry I couldn't fall back to sleep, and I would feel quite hungry multiple times during the day. I never have a problem with hunger, and I've never eaten in the middle of the night. I haven't spoken to anyone about it, but I cannot let that happen during my IMLP taper. I was actually a little nervous that my week of hunger was cause for the stomach issues I had on the bike; but I do think it really was something with the swim as I did feel fine before the swim started.

Back to the OP (sorry for the hijack), I do agree with JK. I don't necessarily increase the intensity of the shorter/lower volume workouts, but I do keep some higher-intensity sessions/intervals/etc. in my plan. It's not all EZ workouts and lower volume. I've only ever taped for a HIM; not yet for an IM.

My philosophy?  Based on Pfitzinger-Douglas ........

Back of the duration, but not the frequency or intensity for workouts.  i.e. Same workouts, just not as long.  Three weeks is plenty.  You should do a "dress rehersal" about 4 or 5 days out that is really short but in the full set-up you will be using and at the race pace you will be going.  That way if there is anything off a bit in your set-up you will catch it and be able to adjust/correct it.

Eat the exact same as you always do.  This will steadily rebuild your glycogen levels to their fullest balancing the correct ratio of carbs to protein (that is the true meaning of carbo-loading, not the usual eating a big meal the night before or doing higher intensity workouts to make your body super-compensate).  You will see a little weight gain if done properly, but that is fine.  You are about to undertake a 9 - 17 hour adventure that will deplete all the stores anyways.