F1-OPT-H1, tax you should pay

If you come to US as F1 and then pratical training, then H1, here is what I believed the tax you should pay.
F1, if you have fellewship or assistant ship, you do not have to pay tax. (even there is 5000 US dollars limit, you could send a copy of the letter from Chinese embassy which indicates that all your income should not be taxed). For sure, you do not have to pay social security tax, medicare, federal tax. In terms of state Tax, you may have to pay it if your state does not honor the treat.
One year practical traning, you should not have to pay tax, you have to use different treat, I remember is 20b, there should have no limit.
H1, you have to pay federal tax and state or local tax. I believe that you do not have to pay social security tax and medicare tax until you get your greencard.it is not a bad idea to pay social security and medicare. Your employer matches your contribution of social security and medicare and you could claim that amount after you retire at age of 65. I paid my social security and medicare and tried to got it back since I consider going back to China. They will not give it back to me. I do not believe we should pay social security or medicare if you do not want to become a US citizen or retire here in US.