I have to start by saying I am insanely jealous and I am sure that you will have a terrific time.
However you raise a couple of good points here.
Lets start with insurance as this is farily quick and simple to organise. You will need a policy for an extended stay, often referred to as a Long Stay Policy http://www.moneysupermarket.com/travel-insurance/long-stay/. You can search online for these through our sister company MoneySupermarket.com. Look out for an exclusions regarding items such as activities you may be planning, coverage for baggage and also clauses around pre-existing medical conditions for both you and also any family member at home for whom you may be forced to cut your trip short in an emergency. This last one is where many people get vaught out ir relatives pass away and they need to return home. You need to ensure that your insurance is geared up for the USA where you need better cover than you do for Asia, especially for medical due to the costs.
Also check that you can extend the policy in case you end up staying away a little longer than origianlly planned.
For your money solution ensure that you know what charges your current providers make for overseas transactions, whether they be credit or debit cards. Many are not fit for use overseas and will cost you money.
I would recommend that you obtain a pre-paid US$ card from one of the market leading pre-paid card providers. Fair FX and Caxton are two of the best here. These can be used to pay for goods and withdraw cash with minimal (if any) fees, are pin protected, backed by either Visa or Mastercard and can be topped up online as you go along. You cannot go into debt and they can be replaced if lost or stolen. You can top up from your current account online as you need to draw down cash.
I use both of these regularly and they have proven to be excellent value for money. Here is a link to some of the best deals http://www.moneysupermarket.com/prepaidcards/ Avoid Travellers Cheques as they are generally expensive to exchange and more hassle than they are worth these days.
One last tip on pre-paid cards is to never use them when checking in for a car or hotel. They will have an amount pre-authorised on them by the hotelier or car rental company which locks the funds even if they don't need to charge you. Use a credit card instead for that.
You should also ensure you have a credit card or two that are designed especially for overseaas usage. Most cards issued in the UK are NOT good value for using overseas as they incur transaction fees and currency loading, making them bad deals. However several issuers have cards specifically designed for travel. These have no fees for buying goods and services and generally offer the best rates of exchange as they tend to be pegged to the standard Visa/Mastercard rates, getting you a better deal than the best buys for cash. Halifax Clarity and Nationwide consistently offer good deals and Sainsburys offer a card with free cash withdrawals, the only one in the market. http://www.moneysupermarket.com/credit-cards/overseas-spending/
Of course you need to pay off your credit card each month and by using online banking this is easy to do to ensure you do not incur interest.
Finally you will want some cash to get you going. Avoid using airport bureaux and high street shops and banks in the UK to get your cash. Instead go online and either pre-order with Travelex/Thomas Cook for airport pick up or use specialist brokers who have online services and some high street picik up points such as ICE and ACE. http://www.moneysupermarket.com/travel-money/
And here is some general advice info for you on your money abroad. http://www.travelsupermarket.com/c/extras/travel-money/
Have a great trip.
Travel expert, www.travelsupermarket.com