> How hard is it for employees to get promoted? > How hard is it for them to get fired?
What do you plan to take away from these questions? Would be more useful to atleast provide your good intentions on what you are looking for when asking.
In this case, those two questions tell someone a bunch of things: whether bad employees might stick around for a long time, whether good employees might want to leave for somewhere with better career prospects, whether there is good process in place to manage and accelerate employee career growth, whether management is doing their jobs right, whether there are wrong incentives or motivators (for example promotions tied to performance alone which incentivizes accomplishing empty goals that promote politically-savvy employees and leave the company hollow).
Famously toxic companies have processes designed to use fear and politics to keep employees so worried about their jobs that they can barely do them, much less contribute to the improvement of the company. Those companies can still survive and give good returns, but they have to trade on market power, and on a personal note they're often unethical.