from dictionary.com, lemma: almost:
"slightly short of; not quite; nearly: almost time to go; was almost asleep; had almost finished"
so, imho, almost still is less then ten years ago
remember, the novel is the only book that's SEMI-canon, meaning the movie can always contradict, don't have it on campus, so soonest I can check is next weekend, sorry
I always was under the impression everyone knew everyone (talking bout the jedi) and I think someone like SD who was a JC member (OB1 said he died, he would have also said that he wasn't a JC member if he wasn't) , so everyone should know him, I think
true about being a padawan and knowing less other jedi though... though if he really was in the JC that shouldn't have been a problem.
see, about your point of Maul being an ex jedi and not born a sith ... there is a quote from GL, though I have to say I don't know it exactly anymore, perhaps someone can help out...
he said that the sith lay low till it was their time to strike and take control of the universe and that time has come during TPM (it's on the TPM DVD somewhere, but I'm not sure if it was on a internet-doc or "the making of"
(oh, and the idea of it being yaddle or jarjar was supposed to be ridiculous to point out I thought your point about it all being a cover-up was rediculous too because mace already wanted to go to the senate to tell that their power to use the force diminished so I doubt they would cover up a fallen jedi)
imho, every jedi can be turned to the dark side, just takes some time for some or a LOT of effort but everyone has emotions which can turn against them if you try hard enough.
ok, the lost 20... it's a scene cut from the movie, but was still filmed, they didn't placed it in the DVD scenes cause it was kinda boring and such, but the lines and such got out on the net ....
see, in the entire order there have only been 20 persons that ever left the order, their statues are in the library, ob1 even looks at one of them when Jocasta Nu asks if he's having a trouble, that one was dooku if memory serves ...
those 20 were the only one that ever left, nothing more nothing less, and dooku was the last one, ten years ago, after the battle of naboo
and that's why most people think it's him, left at the time the order was placed (and very likely the same time kamino got erased)
now to think of it, .... think sw.c named them once in a jc question