I don't know about you guys, but E-Hentai is pretty great. That's how I learned about Sunstone, which isn't even researchographic.
Yes. Except if you're not on Exhentai then you're a scrub.
Also, those "complete a survey" things are always bullstuff. They promise a lot and will never ever deliver, unless you start giving money to one of the companies on there.
Don't ever trust an online competition that you see in an ad space on a website.
If you want actual competitions then there are forums out there who share legitimate competitions.