Answer:
There are some missing details in this question so I shall attempt to answer as best I can.
a. The Fed would set a higher interest rate target.
If the economy is this much above the potential output, it means that the economy is overheated and so the Fed will act to bring it back close to the potential GDP.
To do so, they will aim to increase interest rates. This would make it more expensive for people and companies to borrow money. They will therefore borrow less to fund investments which would lead to the economy's growth reducing and theoretically coming back to the potential GDP level.
b. Unemployment would increase.
As companies find it more expensive to borrow money to fund investments, there will be a decrease in the rates at which people are being hired because less ventures will be formed. Unemployment will therefore gradually rise and will mirror the reduction in economic activity and growth.