1. Mainly word of mouth. Recommendations on the chrons have introduced me to most of my recent new authors, some just starting out, but actually I'm not too worried if they are new so long as they are recommended! I have also tried new authors from the author recommendations on Fantastic Fiction. I first got into John Scalzi by downloading a free ebook from his website.
2. I have bought a lot
of ebooks and have never returned one. I would never take a paper book back into the shop because "I didn't like it" and would probably be laughed right out of the shop if I did. I figure if I make the decision to buy and then don't like it then it's my fault for not researching it well enough eg. samples (actually I rarely read them) so it's my fault anyway