HSA and taxes

[me1]

This is my first year having an HDHP offered through work and also the first time having an HSA. And I am trying to figure out taxes. I have 2 questions
1. If I have money taken out pre-tax and put into my HSA accouunt, does that mean I put 0 in line 2 of form 8889?
2. I thought if my HSA was taken out pretax, it should also be taken out pre- SS and Medicare? I just examined my w-2 and that doesn’t seem to be the case. Is this a mistake on the part of my company or am I misunderstanding how it works?
Thanks for any help!

[MDM]

The answers to both questions depends on whether the contributions were made "through a cafeteria plan" or not.  Most employer-based HSA deductions are made through a cafeteria plan.  In that case (see https://www.irs.gov/pub/irs-pdf/i8889.pdf) the answers are
1. Yes
2a.  Yes.
2b.  Mistake.

Check with your employer to determine your actual situation.

What on your W-2 leads you to believe there has been an employer mistake?