TN Visa & Income Tax question

I answer these questions at forums.serbinski.com

But, since you are not paying UI premiums, you have no need to opt out. In all but 2 states UI premiums are paid solely by the employer. In those states, you cannot opt out.

You will get some small SS if you work at least 1-1/2 years in US and a total of 10 years in US and Canada. the more you work in US, the bigger the SS will be.