@William K.
Answers to your 1, 2 and 3 questions:
1. It's all about removing liens that are attached to the property. The key is attached to the property, not the person.
2. Similar to question 1, generally speaking yes, winner would also have to pay senior liens if they want to obtain title (ownership) to the property
3. I'm fairly certain that second position lien holder (the one foreclosing) would be paid in full. I don't know how the excess funds would be distributed.
Peter's making some really good points. Buying foreclosures isn't for the faint at heart and it's easy to lose a lot of money if you don't fully understand lien positions and such. Sadly, a lot of people make very costly mistakes at auction that are legally binding and can't be undone.
The book Bidding to Buy may be a good place for you to start. It breaks down a complex topic (foreclosures) into understandable terms. If you haven't read that I'd highly recommend it.
Also if it were me, I'd maybe start with only first position liens until you're really comfortable with the process. It's still risky, but not nearly as risky as bidding when a junior lien holder is the foreclosing party. Hope this helps. Good luck!