It depends upon the number and when they are pulled. For hard credit inquires, like inquires in a short period of time will be considered one inquiry against your credit score.
It depends on the type of mortgage. For most mortgages, lenders are required to count a payment for student loans regardless of the status of repayment.
Maybe. Your first call should be to the title company or attorney that handled your closing. In the DC, Maryland and Virginia metropolitan area, many title companies hold money in escrow from the seller to pay the final water bill.