What state are you in? Many states have only judicial sales (which means the sheriff would be involved) and others are mostly non-judicial (which means that a private attorney or mortage company employee would be conducting the sale).
As the prior poster said, it is YOUR responsibilily to check out title, tax liens and the condition of the property. If the property is subject to a federal tax lien and the correct notice was not given, the lien will follow the property. Some sales are of SECOND liens, which means the first lien/mortage would stay in place and you would have to still pay that. The property is always sold as is, so there is no recourse if the roof falls in or the AC breaks.
As for the bid amount, except in rare cases, when I conduct foreclosure sales, I never disclose what the opening bid will be.