I can't find the little book that came with Warcraft 3 to see if you're right about the druid part. That said, when WoW came that was changed.
http://wowpedia.org/Elerethe_Renferal
She was there at the first Cenarion Circle summit and in one of the books (think it was the Shattering) it is stated that she was one of the few female druids that existed before the gender gap was made obsolete.
And the Watchers were part of the night elf army. They were the guardians of prisoners. Just like the prison guards in your country are actually part of the law enforcements even if they're not on the streets arresting people. And they had druids in their ranks, if we do ignore everything in WoW (where the title of warden is awarded to some druids too), you could remember that in the mission where Tyrande goes to save Illidan... there's a keeper of the groove there and treants. Since the gates had been closed before Tyrande busted in, it can be easily assumed he had been there, with the Watchers, as a watcher, for 10k years.
In fact, before WoW the night elven army had 4 branches. 2 of them worked together permanently, the Sisterhood of Elune and the Sentinels, and 2 of them were there, one watching over prisoners, the Watchers, and one learning new things in the way of druidism to battle the Legion, the druids. But all 4 branches were commanded by Elune, through her voice, the Priestess of Elune Tyrande Whisperwind who was the commander of all of them.
This was later changed somewhat in WoW when Malfurion was made to be "on equal footing" with Tyrande in ruling and him having supreme power over the druids, but this was not the case in Warcraft 3.
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I see, didn't get that from your post, the part about druids, sorry about that.
You're right in a way at second part.
As for night elf shamans, even if we exclude them learning from furbolgs in the 10k years they stood together, they did sit in Silithus for at least 1000 years (probably more as Southwind Village existed when the silithid bursted out) keeping watch over the silithid. So they had time to sit in a desert with hostile elementals and ponder of the meaning of life.