I believe so, though I'm sure Cryptic has a way of tracking which site they were created on.
At that point, they didn't.
That said, I'm betting at least 80% of that number was people interested in STO. Because super-hero games are even more niche than sci-fi games and City of Heroes basically couldn't have more than 300k people even interested in playing at its peak. Which is impressive because comic books themselves are considered a hit if they sell 60k copies a month.
The flipside is, I'm also sure the Trek brand attracted people who didn't know what an MMO was, who'd never played one, who'd never played computer games, who'd never pay a monthly fee to play (TrekMovie was full of people in that category), who were hoping this would be an improved Star Trek community site, any number of things.