I recently signed up on PINCHme and so far I'm happy. I had to answer a few questions (what products I like) but it took less than 10 minutes. I get some emails from them, like one every few days. I just delete them. I haven't got any from third parties. Today they released some of their free samples (they supposedly do every two weeks) and I got to order 4.

1) No the registration process is not too long. You have to just fill a few surveys on you.
2) No, I have never got any mail or calls from their party companies yet.
3) Well if you are lucky only then you will get free samples. In most cases they will only show you their past samples which is Out of Stock.
You can check out their Facebook page to see the number of people who never got to see any new samples just like me :(