For what it's worth, I actually think the amount of detail given in the OP was close to appropriate. A lot of FT posts are way too long and rambling, with irrelevant details, but IMO zoonil's post was spot on. You gave relevant information, without emotional or ancillary content. This is approximately the same level of detail that I try to give when I'm writing to United to request compensation. I think the main issue is that you have so many distinct (and legit) complaints; I concur with jsloan's suggestion to separate the return flight from the outbound. Also, combine complaints 1-2, 4-5, and 5-6, so you have four succinct complaints:
1. Transpacific business class flight canceled for mechanical reasons. And then the replacement flight returned to EWR, also for mechanical reasons. Caused a 2-day avoidable delay.
2. On top of that delay, the only option offered to get to your destination even 2 days late was in economy (see below re: "downgrade" term).
3. 5 checked bags lost for 5 days. Major personal and emotional consequences.
4. The special vegetarian meals that you pre-ordered were not available on two consecutive business class flights.

With that said, jsloan is certainly more experienced and authoritative than I, so take my comments with a grain of salt.

Final note: IIRC, what happened to you isn't technically an [involuntary] downgrade. United promises to get you to your destination in your purchased class of service... but they do not promise to get you there in a timely fashion. If your flight is canceled, they will happily reaccomodate you in business on the next flight with open space, which is probably 17 days later! I assume that they gave you the option of flying sooner in economy, and you said you'd rather take that (you may not have been aware that you had other options, but I'm presuming you would not have chosen to wait several more days for business). Anyway, you're still due a refund, but you may be better off avoiding the term "downgrade", or at least keeping in mind that unless I'm guessing the facts wrong, this counts as a voluntary downgrade because you wanted to get to India in a timely fashion. You were reaccomodated in a lower class of service, for which you are entitled to a refund. Whereas if you'd flown in Y on your original flight, that would have been a downgrade, for which you'd be entitled to both a refund and compensation.