How to relocate to the US [closed]

So, I am a software engineer, from eastern Europe. Let’s say that I want to move to California, and I’ve found an employer that wants to hire me. Then what?

I know I must apply for work visa, but I mean to ask – Is it easy? Is it fast? Is it common? How do I change my employer then? Start my own business or go to University? Do you get US citizenship when you live there for 5 years or something?