Well, personally, I like to keep tabs on seiyuus. Tbh, apart from animes and mangas, I like to keep a lot on certain things that interests me - like a mangaka's other works, an anime studios/makers' projects, a music band's other albums, the different voicing done by other seiyuu's and stuffs like that...I doubt there are really that many people that keep regular tabs on Japanese voice actors. I'm a manga person, anime is secondary and I only watch it when I'm bored after haven't watched any new episodes for a few weeks or even months. Let alone that I start digging into the private affairs of the voice actors (which I really don't care about). The only thing I ever amused myself with was trying to find the same voice actors in different animes I watched based on their voice alone. In fact most of the time I don't really want to know who is voicing who as that might ruin the way you look at a character. I still find it weird to look at Mako of LoK (cartoon ok, not anime) who is voiced by the actor who played Bud Bundy in Married With Children.
For seiyuus, it's not like I follow all of them, but mainly voices I have really been a fan about. And sometimes, it can prove handy. Like Steins;Gate is one of my favorite anime in all-time list but initially, what made me watch it the first time, wasn't the hype, storyline ect... but seiyuus. I got into it because Hanazawa Kana was into it (voicing Mayuuri) and she got the cutest voice I've ever heard (big fan of her) and add on to that, there was Miyano Mamoru - who got the best evil laugh and one of the unique voices in seiyuu history.
I don't quite agree with your assessment that it might ruin the way you look at a character. In fact, I think a seiyuus is the one who makes you feel the emotion of a character in anime. So, in a way, knowing a seiyuu better enhances a character as you know that that voice connects with you.
Back to Hirano Aya is, or now was, very popular. Though, not a fan of her, this made pretty much headlines. So, I think this news was far more popular and known than what you think of.
No, FT was cancelled for other reasons mentioned before. That being said, Hirano Aya basically in nearly jobless right now thanks to that, so in a way, Lucy is temporarily mute now.Don't believe they would cancel an anime just because of the voice actor being sexuallly ... hum... how to put it nicely... exposed.