I don’t know if I’d call myself a musician but I’ve taken courses. I don’t think th ensembles are too difficult to get into. Here is some more information about them: https://www.haverford.edu/music/applied-music-study/instrumental-study
In terms of size, Haverford is small but the consortium really mitigates that. Most students take classes at Bryn Mawr which is less than a 10 minute shuttle ride away. People take classes at Swarthmore and Penn less frequently because it takes longer to get there and people are lazy, but it’s completely doable. I would say most students go to Swarthmore and Penn if there’s a department that’s particularly strong (like Linguistics or Film for Swarthmore and Business for Penn) or a unique elective class that Haverford doesn’t offer.