You will need to get yourself a US driving licence. First of all the Americans have no understanding of what a foreign licence. The insurance companies wont accept a Internationl driving licence, and the law says you have to have one if your resident there for more then 28 days. When I purchased and insured my car, I was allowed by the insurers to drive on my Irish licence but they would not cover me after 1 month unless I had a US one. Shop around, prices vary wildly I got mine for about $80 a month. You can usually pay monthly so need only pay for as much as you use.
The US test is very easy. You wont believe me until after the test. Go to the test centre and get a booklet. Memorize all the info and take the multi choice test. Again a piece of cake, wrong answers very wrong etc. Test itself usually just a spin around the block, three point turn, driving straight forward into a coned parking space, nothing difficult. Hope that helps.