Wouter Willemse , Aug 06, 2012; 03:45 a.m.
There is no such things as "the best settings", it all depends on subject, the light you have, circumstances - and part also your personal preference. So nobody can really say what is best in this sense.
To blur the background, you need to use a wide aperture, and be relatively close to your subject.
Given your question, I think you might be helped more with a good introduction to the basics of photography; the book Understanding Exposure by Bryan Peterson will give you the knowledge and understanding that would answer both your questions.