How do references work in IM as you jump ship?

Hey guys -- thinking of jumping ship to become an Analyst elsewhere. Only thing I'm worried about is that I know my boss (who I do 95% of the my work with, though several PMs involved at various points) will be unhappy if I leave as he expects that I work under him for another 3yrs before becoming an Analyst here (though given how things are going, I'm increasingly skeptical this will ever happen). So I can't ask him for a reference as I'm afraid he'd tank my chances at another firm. This is also my first and only job (been here for over 4yrs) so no references I can ask outside of the firm. I think background checks usually ask for a couple references (I needed 2 to get into this firm, used folks from internships).

Two questions to you all:

1. How many references do you need to provide when moving jobs? 2 or 3? Any cases where you don't need any?

2. Who do you have to ask? I'd probably ask one or two PMs here, but can I also ask a friend who's at the same level as me? Or potentially ask a friend who's an Analyst? I just want to avoid asking my boss but how meaningfully close does the reference need to be to me work?

Much appreciated to you all