I don't think anybody here expects personal/sensitive info about investors.
In contrast to Bitcoin, alts had unique addresses (which had its own set of pros and cons during the sale). I can welcome a third party to look into the movement of these[1].
Anything that's on the blockchain is fair game though and you could quash most of the allegations in the OP by showing how those coins moved and where it all resides now.
You can see this yourself by simply following the original Bitcoin address (it requires only a few jumps). And no, it isn't possible to sign a message from a multisig address especially not from a setup that doesn't display individual keys (it would require compromising all three seeds).
TG (or any chat contraption) is not a good way to communicate with investors.
Bitcointalk was never the way for communicating with NVO; it was their Slack and now it is their TG channel.
How did the bagholders learn about the vote?
Reddit, Medium, TG, Slack and some Discord groups made by individuals.
It seems very short (2 weeks) and on short notice.
Well, this seems contradicting. A certain side is complaining that refunds are not happening fast enough ("that we are stalling"). It can always be prolonged by a bit if need be.
Did the team or the escrow e-mail registered users?
This is where it gets complicated and out of my hand. Allegedly, nemgun had control of the domain(s?) and email(s) (which includes the investor database) before the dispute between the team members arose due to Yanni's disappearance and other stuff.. Some time after it started, Yanni temporarily appeared and allegedly took back control only to disappear again (temporarily?). There's no real way of knowing what exactly happened down there[2] nor whose story is true (hence the vote). I've sent Ton a message about the email database after I've read your question.
Does this mean that BCH and other major forks will be distributed to NVO bagholders? Simply stating that plus some blockchain proof of the escrow holding those amounts would be much better than this endless back-and-forth.
Well, they were already calculated within the releases[3]. Forks were redeemed and released to nemgun as part of his share of the milestones (he barely touched any other coins until one - two months before this disaster) under the claim that they would be used for development purposes. I have the chain data for all of those, including the parts that remain unspent under his control (or yanni's, depending on which side of the story you believe..).
I also have a list of forks that are still within our possession (provided by Anduck); but I'm uncertain of their total value at this time as most of the time available is spent responding and debunking nonsense here and elsewhere.
[1] Though I wonder why the attempt at burning me on a stake (by certain individuals), when I only ever held 1 alternative currency.
[2] It's similar to this thread; nemgun claims X happened, Yanni claims Y happened. Ton sides with Yanni (his original co-founder). Neither side has provided something that I would consider absolute evidence of certain events happening. Therefore, as a neutral third party I proposed that holders vote on the outcome (which they currently are).
[3] Based on the complete audit (which includes the forks), there are 50% more funds available than the minimum requirement by the milestones. This kind-of-dispels the 'team exit scam' claims, but I'm sure that certain individuals would disagree.