When my employer makes a contribution to an employee 401k account, are any taxes payed by the employee (e.g. FICA)? And does the employer match amount show anywhere on the employee's W-2 or 1040?
The 401K match has limits, but it is not taxable until you withdraw the money from the account. You can think of it as an initial lump of interest or gain.
When you leave the company you are allowed to keep it, if you are vested. You can then roll it over into a IRA, or another 401K.
When you withdraw money in retirement you will pay taxes on the match and all the gains from the match. Taxes on what you contribute will depend on if it was pre-tax or post-tax, or if it was deposited into a Roth IRA.
The amount you deposit pretax is noted on the W-2, which you attach to the 1040 form. The company match does not appear anywhere on the w-2 or 1040. It should show on your 401-K statements. Those statements should also tell you how much of the match has been vested.
Employer matches (even for Roth 401Ks) are put into traditional 401K accounts and are treated as pre-tax income.
Traditional 401K plans are tax deferred accounts, meaning you won't owe any taxes on it this year, but will have to pay taxes on it when you take the money out (likely after retirement).
401K contributions (including the match) are reported to the IRS and are entered in box 12 on the W2 form.
For the 1st part of your question. Yes the other taxes still apply. You are only deferring your income tax, not the other taxes.
Read the 3rd paragraph: