Regarding stock options expiring 3 months after leaving the company, it doesn't have to be this way and a lot of startups are moving in the direction of 10 year exercise periods.

I think Quora was the first to do this: https://dangelo.quora.com/10-Year-Exercise-Periods-Make-Sens...

And keeps an ongoing list of companies that offer extended exercise windows: https://github.com/holman/extended-exercise-windows

As somebody who has personally experienced every aspect of the stock option lifecycle (which fortunately worked out for me), I would never take a job at a company [1] if they didn't have an extended exercise window. The 90 day expiration period creates a massive gap between the risk/reward of equity for founders and the risk/reward of equity for employees, when the whole point of giving equity is to align those.

1: Assuming it was the type of company that compensated people with stock options