Lostgirl,
Take half the clothes and twice the money!!.
Inform your credit card provider that you will be using your card in NYC for the duration; if you did not do this your card could be stopped.
Good walking shoes are a must, NY is no place for heels of a day as you'll do a lot of walking around. A good street map is a must have too.
Also obtain a good map of the Metro system along with a metro fare card (this can be topped up with dollar bills. It costs $2.25 per ride). Do work out beforehand what train you need to get on their Metro system (as they also run express trains down the middle of their railway lines). Signage is not good and can be confusing to the visitor.
There is now a Magnolia Bakery on the corner of 49th Street and Avenue of the Americas (6th Avenue). Infact there are now three branches of Magnolia Bakery in the Manhattan area. They are also open late into the evening. They have a website and the cupcakes are fab.
Stores generally do not open until 10am but stay open late. There are lots of designer stores along Fifth Avenue. Do visit Macys down at 34th Street and claim your discount voucher from the first floor visitors area (bring photo ID to prove you are from the UK). Bloomingdales is worth a visit too.
Hop on hop off bus can be expensive to use, probably not worth using overall.
Statue of Liberty tickets need to be booked in advance of travel, be prepared for long security waits if you do this. Probably not worth doing if you are only in NYC for a couple of days. Empire State Building though is worth a visit as is the Rockefeller centre (you can watch the ice skaters in front of the building).