Before I state my answers to the questions, I'd like to state that I haven't been roleplaying with a lot of people outside the group I run. I did a few years ago, but, I just wanted to state that because it has a big effect on my opinions. I guess what I'm trying to say is that "I haven't gotten outside," meaning other roleplays. But, within my group, I roleplay all the time!
1) I've never really thought about it too much. Honestly, I just rp with whoever is willing to roleplay with me. Though, designs and the amount of development a person has put into the character also has played a role as well. I do avoid roleplaying with people if I notice that they tend to start drama OOC.
2) I have been the person who everyone has wanted to roleplay with. When my character in the group I run was Alpha, I' get swarmed a lot with people wanting to rp with me.