Real estate question (foreclosed homes)?

I am looking into purchasing a foreclosed home. They have several auctions every weekend through the Sheriff's dept. and I was thinking about checking one out however, I am ignorant to the whole real estate game. I know with the foreclosed homes you don't get very many details regarding the home, which is no problem because I wouldn't mind a fixer upper to begin with. What is the procedure? What should I be weary of? Anything else I should know before I begin hunting. I would obviously need a loan. Which bank has the lowest interest rate or does it vary on your credit? Also, why does it hurt my credit just to check it unless I am applying for something. Any input or details would be very helpful. Thank you.