到底怎么分EB1, 2, 3啊？

I'm totally blind to these issues, badly need somebody to tell me the basics...

What kind of people can apply for EB1? Only university professors and postdoctoral? Is that significantly faster than EB2?

If for research position in companies, does that mean EB2 is the norm? Will working in big companies be better than working in small companies?

I also heard that different areas has differnt speed of processing cases? For example, new york and Ca are the two slowest places, is that true?

thanks you so much....