IM MOO and Long Course Worlds

I think it depends greatly on your endurance background.  If you've come from a strong marathon/ultra marathon running background, then it's less of an issue than if you're coming from an Olympic distance triathlon background.

I know a few people who do 3 Ironman races per year, sometimes within 6-8 weeks of each other.  They typically take 1 week completely off, then swim the 2nd week, bike and run the 3rd week and have 1 week of solid/long workouts, then begin to taper for the next IM.

I would talk to your coach (or get one if you don't have one) because when you're pushing the endurance envelope this much and risking potentially long-term injuries, professional advice is the best investment you could make.

First and foremost, congratulations on your selection for the Long Course Worlds.

It will depend on you and how you recover, but recovering from a HIM is very different than recovering from an IM. I know for my own experience, I've barely even been sore after a HIM. After my IM, I had some soreness for several days and I experienced a marked fatigue a couple of weeks afterwards. I was in much better shape for my IM than any HIM. I would say that having a race - or something else - to shoot for after my IM would have helped my motivation though.

Getting a coach was a good suggestion.

You should be fine, just use IM MOO as a train up for Worlds. Rest and recovery in between.