After a foreclosure, if the home sells for less than the homeowner owes, will the homeowner be responsible for the difference? Who pays legal fees?

Yes, the homeowner is responsible for the balance and the fees.

Your mortgage agreement (promissory note) should spell this out. But its generally true of any asset used as collateral for a loan. If the asset is reposssed and sold for less than the balance of the loan, the debtor is still responsible for that balance. They are also usually respopnsible for any fees involved in retrieving and disposing of the asset.