Hi hurricane,
A) Rarely. But it does happen.
B1) I try to, but that doesn't always work.
B2) I rarely skip an unknown word. I like to learn new words; in fact, I keep a MS Word document on my desktop where I add new words that I have learned.
B3) Yes, I use two sources.
B3i)
Dictionary.com. I have given you a hyperlink, but here is the actual link: http://dictionary.reference.com/
B3ii)
Gurunet is a very handy software program. I can alt click on any word in any application, and, as long as I am connect to the Internet (which I always am), I can readily find out the meaning of any word. If I am using MS Word and I don't know the meaning of a word, I just alt mouse click it, and up pops the definition. If I am on the web and I don't know the meaning of a word, I just alt mouse click it.
(I have given a hyerlink to gurunet above, and here is the actual link: http://www.gurunet.com/home.jsp).
Plus, Gurunet has other reference stuff like arts and culture, business, food & nutrition, general reference, government, language, legal, leisure, medical, military, people, places, religeon and mythology, science and tech, shopping, sports, and zoology. Gurunet has
won rave reviews. But it is a subcription based service at about $30 per year.
I hope that helps.