Legal Question in Immigration Law in New York

You may want to have the contract reviewed by an employment attorney in New York before signing to confirm how enforceable the contract really will be, and how one sided it may be - for instance, does it in fact guarantee an offer of employment for the next year in addition to requiring it from you. Your friends are, in general, correct as to the typical results of these contracts - often they are not enforceable. But a review of the actual contract before you sign is important.

If the I-140 is already approved, then you are eligible to file for adjustment of status without the prospective employer being required to sign any additional forms. However, USCIS usually requires a letter from the prospective employer regarding its intent to employ you once the I-485 application is approved.

As long as the I-485 is pending for 6 months and the I-140 is approved, you can "port" to a new employer without needing another labor certification.

As far as the contract goes, it is beyond the scope of immigration law, so I can only advise you to contact an Employment Law attorney in your State.