The briefing is needed to provide more foundation for the finance team because they are not well versed in the international aspects of finance. Provide a briefing describing when and why central banks buy either their own currency or the currency of another nation in an effort to control exchange rates.

Foreign exchange refers to money denominated in the currency of another country. The exchange rate is a price-the number of units of one nation's currency that must be surrendered in order to acquire one unit of another nation's currency. In the spot market, there is an exchange rate for every other national currency The Forex market is essentially governed by the law of supply and demand and is generally not regulated by any government or coalition of governments. This is true in the U.S., where participation in the Forex market is not regulated. The prices set for each country's money is determined by the desire of those trading to acquire more of it or to hold less of it. Each individual acts on the belief that he or she will benefit from the transaction.
It is the interaction of demand and supply of foreign exchange that results in the movement of currency prices in the Forex market.
(Wikipedia)
A central bank can only operate a truly independent monetary policy when the exchange rate is floating. If the exchange rate is pegged or managed in any way, the central bank will have to purchase or sell foreign exchange. These transactions in foreign exchange will have an effect on base money analogous to open market purchases and sales of government debt; if the central bank buys foreign exchange, base money increases, and vice versa.

Accordingly, the management of the exchange rate will influence domestic monetary conditions. In order to maintain its monetary policy target, the central bank will have to sterilize or offset its foreign exchange operations. For example, if a central bank buys foreign exchange (to counteract appreciation of the exchange rate), base money will increase. Therefore, to sterilize that increase, the central bank must also sell government debt to decrease base money by an equal amount. It follows that turbulent activity in foreign exchange markets can cause a central bank to lose control of domestic monetary policy when it is also managing the exchange rate.
Monetary policy can be implemented by changing the size of the monetary base. This directly changes the total amount of money circulating in the economy. In the United States, the Federal Reserve can use open market operations to change the monetary base. The Federal Reserve would buy/sell bonds in exchange for hard currency. When the Federal Reserve disburses/collects this hard currency payment, it alters the amount of currency in the economy, thus altering the monetary base.
Hence suppose the target exchange rate set by the Fed is 100yen per dollars. If the demand for the dollars temporarily increases, to maintain the target exchange rate, the Fed can buy dollars and the opposite is also true.

Next, discuss and advise if the firm should reinvest its profits in a country where they are generated rather than repatriate them to the United States because of tax implications. Consider if the exchange rate is a bigger concern.

Yes if it the corporate tax rate is lower in the host country than it will be good to reinvest other wise repatriation is preferable. But one has to take implications of foreign exchange risk also.

Implication of Foreign exchange risk on Firm

Firms must constantly assess the business environments of the countries they are already operating in as well as the ones they are considering investing in.

Types of exposure

Transaction exposure
It is the extent to which given exchanges rate change will change the value of foreign currency denominated transactions already entered into.
Measurement of Transaction Exposure

* Transaction exposure measures gains or losses that arise from the settlement of existing financial obligations, namely
o Purchasing or selling on credit goods or services when prices are stated in foreign currencies
o Borrowing or lending funds when repayment is to be made in a foreign currency
o Being a party to an unperformed forward contract and
o Otherwise acquiring assets or incurring liabilities denominated in foreign currencies
http://www.businessfaculty.utoledo.edu/pkozlowski/FINA3500/ch08.ppt.
Translation (Accounting) exposure
The change in the value of a firm's foreign currency denominated accounts due to a change in exchange rates.

Economic exposure
It measures how greatly a firm's present value of future cash flows is affected by unexpected exchange rate fluctuations.

Comparison

Transaction exposure arises whenever a company is committed to a foreign-currency-denominated transaction. Since the transaction will result in a future foreign currency cash inflow or outflow, any change in the exchange rate between the time the transaction is entered into and the time it is settled in cash will lead to a change in the dollar (Home Currency) amount of the cash inflow or outflow.

Transaction exposure is a subset of economic exposure. It is because the currency fluctuations affect more than currency transactions. For example an increase in inflation in USA may:
1. Lower value of outflow from US (transaction exposure)
2. Increase subsidiary's US sale
3. Raise financing cost in US
Thus domestic firm has also foreign exchange risk according to the economic exposure. For example, When the value of the dollar falls or weakens in relation to another currency, prices of goods and services from that country rise for U.S. consumers. It takes more dollars to purchase the same amount of foreign currency to buy goods and services. That means U.S. consumers and U.S. companies that import products have reduced purchasing power.

When the value of the dollar falls or weakens in relation to another currency, prices of goods and services from that country rise for U.S. consumers. It takes more dollars to purchase the same amount of foreign currency to buy goods and services. That means U.S. consumers and U.S. companies that import products have reduced purchasing power.

At the same time, a weak dollar means prices for U.S. products fall in foreign markets, benefiting U.S. exporters and foreign consumers. With a weak dollar, it takes fewer units of foreign currency to buy the right amount of dollars to purchase U.S. goods. As a result, consumers in other countries can buy U.S. products with less money.

Thus one has to compare the both the cost and benefits of both the aspects (Taxation and foreign exchange risk) to make the final decision regarding repatriation of profit.

Reference:
1. www.en.wikipedia.org
2. MACRO ECONOMICS: BY MISHRA & PURI
3. WWW.REDIFF.COM
4. My past papers