I want to know what are the salary deductibles if I were to work in New Jersey. I am a foreign citizen with Optional Practical Training.

As far as I know the deductibles are:
Federal tax (whats the rate? Any different from people not under OPT?)
State tax (same as local resident?)
Social Security tax (is there such thing? If yes, what is the rate?)
?? What other things that will be deducted?

If you are on OPT, then you are under the F-1 or J-1 visa program.

You are subject to both U.S. and NJ income taxes. Federal tax rates start at 10%, then 15%, then 25%, then 28%, then 33%, and finally 35%.

Not sure about NJ, but you can access the state government website to get the tax rates.

Since you are still under the F-1 or J-1 visa, you are NOT liable for either Social Security (6.2%) or Medicare (1.45%) taxes.

NJ also has a deduction of disability and unemployment insurance.