Because you have no credit history, businesses such as the phone company will typically require a security deposit and it is rather difficult to obtain credit. If you plan to stay more than a few months, you should start working on establishing your credit. If this doesn't work, you can also apply for a secured card, which is guaranteed by a deposit you make with the card issuer. Note that it may take several months before your new account appears on your credit report. Investments Be it mutual funds or stocks, you are on your own.
Profits are taxable and somewhat complex to calculate so be prepared to deal with that.
Many guests researchers who are under a tax treaty and do not pay taxes on their income from NIST can take advantage of their status. V. Taxes See the separate Tax section. Especially the 'Deutsche Bank' caused major head aches. Wire transfers through them usually arrived within a week. And you still get a reasonable interest rate.