I am 125 miles west of New York City if you need help on this side of the country. I have hosted many riders and currently have an Argentine and US registered Aussie bike in my garage if you are thinking of storage.
Insurance: Progressive and Dairyland have been used by nonresidents without incident. There is a broker in Florida that offers insurance,
Overseas Visitors you can cancel anytime and may wish to pay for a 30-60 days at a time. Others have had luck with competative companies.
Bank Accounts : I asked at my bank they require you to be there in person with your passport and allow 7 days to get things sorted and activated. You can always tour the northeast and return if need be.
Gas Cards and PIN numbers : If you can get a US Visa or Mastercard or even a Discover Card it would make things easier. Even some of my Canadian friends can't use their cards because the US Gas Pumps do not recognize their PIN numbers. I used a Discover Card across the US last summer.
Shipping : Information already provided. However it maybe cheaper to ship to Montreal or Toronto. Also for some reason my Irish friend was held up for 7 days in New York City waiting for his bike. Also he came out of the parking lot and had to learn to drive on the right side of the road in awful traffic. BTW I have a friend who hosts motorcyclist in NYC but we will need a know in advance of your arrival since he travels also. His place is right on Broadway.
USA : Yes it is very big and one can even take their time and enjoy the back roads coast to coast. It took me 8 days of back roads to get to California from Pennsylvania. You want to stay way from the highways for scenic travel. Bring a tent camping is cheaper and plentiful. Adv Rider is a great help in the US and if you own a BMW join
BMW Motorcycle Owners of America
US Address : Mine is available and has been used by many a traveler. However if you plan to use my address and purchase a bike in Pennsylvania you will need a Pennsylvania Drivers License since it appears you are a resident here. If you buy outside of Pennsylvania you can use the address but maybe required to show different forms of ID based on points. For example you need 6 points for New York State, a passport is worth 4 and a photo ID is worth 2 points so you pass. In Florida and California you just show any ID buy a bike using my address and you are good to go.
The future according to the people that monger fear is the day is coming when your address, drivers license, insurance papers will have to match and if you purchase an out of state bike you have 30 days to get it registered where you live. This helps the US to sort out illegal aliens and stop part year residents in different states from having two or more addresses. I asked about foreign visitors and the day is coming when it will be too complicated to buy in the US without being a resident. I know its a pain in the ass and it is coming in 1 to 5 to 10 years depending how cooperative all 50 States are and since most are broke the federal government may just hold highway money from them to force them to comply. So much for freedom and the country that opened its self to the world to come here.

Wait till we all have to have a national drivers license and or ID card.