Let me address the payment/title part of the question:
Have the seller get you the contact information for an officer at their bank. YOU talk with that officer to get payoff information. The next step will depend on whether they owe more than the selling price. In either case, this is a common issue that can be handled between you, perhaps your banker and the bank holding the lien. Once you get the numbers, visit with your banker for their suggestion. Do not be concerned about this-- basically if your banker is happy with the process (draft for title, etc) you should be happy.
Bottom line, you do NOT turn over money to the seller and HOPE that they pay off the lien. And a quick call from seller to their bank should confirm this is NOT the way it is done.