RSUs are treated as cash income at vest and taxed at same rates.
Stock buybacks benefit general shareholders (i.e. beyond employees) since they push up stock value without causing a taxable event. The alternative is dividends which are immediately taxed.
About -25%. Current campus size is roughly what it was in early 2014.
The difference in the housing market is that instead of being 28-year-olds who live in apartments, all those MTV Googlers are 38-year-olds with families who are sitting on a couple million in stock compensation each.