Believe it or not it's been super UNclear how much my husband's employer is paying into his 401k plan? We understand it is a 3% match, but what does that mean exactly? is that 3% of the SALARY? Or 3% of what you pay to the 401k for that year??

This is something that  HR can clearly define, but in my previous jobs, it has been 3% of  your salary.  So, say for example, 3% of your salary is $1,500, your employer would match that so that your total 401K account is $3,000.  However, since the maximum is $16,500, if you put into your 401k $2000, then your employer wouldn't match the extra $500 you put in.  Thus, your total account would still be $2000+$1,500 = $3,500.    In other words, 3% or $1,500 in this case is the maximum your employer would match you.