1) You should either fill out another one, or tell the immigration officer that the affidavit should be on file already (this will not be a good thing to do, becuase you should have a backup copy of EVERYTHING!)
2) Once entried the U.S., the first thing is to apply for an alien card (green card) at the airport custom (port of entry). after you settled, go to the Social Security Administration Office (SSA Office) to apply for a Social Security Card. Make sure to bring your passport! You will need a Social Security Number to apply for anything from driving license, bank account, to cellphone.
*Overseas property is a good source for financial support on the financial affidavit; however, you are subjected to be taxed for gains on your overseas property and investment.
If you have more question, welcome to ask me! I can read and speak Chinese, just don't know how to type ;)