People need to understand a simple concept: if you wouldn't feel comfortable saying something in front of a packed auditorium, you probably shouldn't say it in a public forum online.
Absolutely. If you're comfortable voicing the opinions you put online anywhere else, then you're probably going to be miserable working for a company that refuses to hire you based on those opinions. If you're an asshat who likes to piss people off, then you're not likely to be working for anyone too long, anyway.
I'm not a big fan of the trend towards using online personas against people, but I see it as a reverse filtering effect. "You don't like me. I don't like you. Glad we know this now."
Living on Earth may be expensive, but it includes an annual free trip around the Sun.