You need to check with a title co to make sure there are no other liens on the property. Just because they are selling it via a tax lien sale does not mean it is free from other liens.
You need to drive by and see for yourself if it is vacant. If it is owner occupied or tenant occupied you will be responsible to evict. There are rules and laws that must be followed in this process, check with a lawyer. As far as info related to the tax lien again, check a lawyer.