First of all, if the owner is still in the home after the auction, which can happen, you will need to contact your local law enforcment authorities and proceed with a "Forced Eviction". These procedures can very from city to city so be sure to check with your local authorities and follow the guidelines set forth.
If you really want the house, try to get it before the auction. The truth is, auctions are nothing more than a roll of the dice and if you find yourself bidding against someone else who really wants the home, you will most likely pay more vs. negotiating with the seller and what they need to just get out from under it because they are desperate to get out!
As for the liens, regardeless of the method in which you buy, auction or traditional sale, you need to make sure you are buying title insurance. Title insurance gives you the right of enjoyment and therefore protects you from future liens. Truth his, auction or not, you want the seller to provide you with clear title, if they can't, then I wouldn't buy it.
As for the liens being calculated in with the purchase price, well, sure why not. If they are going to sell the home at auction, they (the sellers) need to make enough to pay off the debt including any liens. Chances are, if that is the case, the auctioner along with the seller are going to set a reserve price which means, if they don't get any bids in that amount or more, it won't sell. If you're serious about this home, you wont clear title so that means, you want to buy it at a price that allows them to clear off any and all debt.
Good luck and find a local Realtor, they can help you in determining price and how local auctions work in your area. Not to mention, the Realtor can also help in the offer process before auction.