RSU grants are afaik usually on a per unit basis based on the price when you start. So if the current stock price is $20/share and you get $20k worth of RSUs then that means you get 1k shares. If the value per share goes up to $100 then your RSUs are now worth $100k. This is why some tech company employees have massive stock compensations, the stock has gone up a lot since their initial offer.

Im sure there are different ways of doing it, but this is not my experience. In my experience, you get X RSU stocks, and or Y dollars worth of stock. It is then locked up for 3-4 years so if you took stock it may have increased in value.

This depends on whether your RSUs are measured in $ or units.