Very little is known about either V.F.D. or Beatrice; how she died, and how her story is related to that of the Baudelaires. Similarly, little is known of the Snickets or the deceased Baudelaires. If you know anything else, please send it my way.
Lemony Snicket has a tattoo on his left ankle, a reminder of a happier time in his life. (8.214)
Also, The Unofficial Lemony Snicket FAQ is a great resource. He's done a better job than I have the energy for.
You may also be interested in my conclusions on The Unauthorized Autobiography.
Here are the facts:
Book 3: page 126
I [Lemony Snicket] have seen a woman I loved picked up by an enormous eagle and flown to its high mountain nest.
Book 4: Dedication
My love flew like a butterfly/Until death swooped down like a bat...
Book 6: page 26
"Ah!" Jerome said. "You're [Violet] adventurous! . . . Your mother was adventurous, too. . . . We hiked up Mount Fraught with some friends--gosh, it must have been twenty years ago. Mount Fraught was known for having dangerous animals on it, but your mother wasn't afraid. But then, swooping out of the sky--"
Book 8: page 72
...I would have been able to tell them a long and terrible story about men and women who joined a noble organization only to find their lives wrecked by a greedy man and a lazy newspaper...
Book 8: page 77
The word "Beatrice" reminds me of a volunteer organization that was swarming with corruption...
Book 8: page 76
"This page [of the Quagmire journals] . . . has on it a long list of dates. It looks like something was going on every twelve weeks or so."
Book 8: page 89
It is useless to tell the Snicket story, because it happened so very long ago, and because there is nothing anybody can do about the way it has turned out...
Book 8: page 109
...experts now suspect that there may in fact be one survivor of the fire, but the survivor's whereabouts are unknown.
The Slippery Slope clue is available in the gallery. It says "Two will disappear and never be seen again." But then, it also includes the words 'red herring,' so one can't be too sure that those ladies with the powdered faces are the next to die.