How does a Tax Foreclosure work if the person whose property is being tax foreclosed on also has a bank loan?
It depends on the state/county/whatever, and what priority lien and such. Usually the lien isn't wiped, and you now either start paying the loan on it, or risk them foreclosing on you.
Do you recommend books and/or Links for me to learn on how to buy properties for rent or resale?
Yes, I absolutely do.
Don't get into real estate investing without lots, and lots, and LOTS of reading.
(More on this below.)
What other fees are added when buying a foreclosure property?
It will vary based on the transaction type. A "foreclosure property" doesn't necessarily mean at the auction, often people refer to REOs by that as well. You will need to know more about what specifically you are trying to do to answer that.
Should a get an agent?
Again, depends on the transaction type, your level of experience and knowledge, and what you're trying to accomplish.
How do you do it?
And once more, it depends. I've done rehabs, buy and holds, notes, auctions, owner financing, etc. Each one was different.
I mean no offense with this, but your questions are very, very basic. Try not to get into anything until you have acquired a lot more knowledge. Start by searching these forums for real estate book recommendations. There's a few threads with recommendations. Then start going to biggerpockets.com and reading their forums on a regular basis.
Good luck!