When you buy at the steps you are buying whatever is foreclosing. So if it is the second foreclosing then you still are subordinate to the first. If it is the first foreclosing the second is wiped out. So if it was the first foreclosing the second is screwed. No he cannot come to you for anything.
The second gets wiped out no matter who takes it.
Yes there are other liens you may have to deal with. Property taxes and IRS liens are the most common. Other issues may involve incomplete work, say the owner was in the middle of a permitting process or something of that nature. The other issue you brought up are mechanics liens. You need to check dates on the mechanics liens to see if they will be subordinate to the first foreclosing.
