Yep FB offers undergrads from some universities 100-120k, plus 50-100k signing bonus, plus $100-125k in stocks from what I've heard.
Even non-CS majors. If they studied a quantitative field, can code, and cleared the dev interview, they got that offer.
You have to stay a full year at the company otherwise you have to pay it back. But yes, it is all upfront; cash.
In general, a publicly traded company is not going to give that kind of package to an undergrad. Maybe $110-120k in salary, but the stock amount is more likely to be around $80k vesting over 4 years.
Would be alot different than 100k "signing bonus", more sane tho.
I'd say $100k salary is very typical, as are the RSUs (vesting over 4 years as you said).