Almost all the biotech centric classes can be taken by non BEP students, and it is the same deal for E & I classes. There is no priority given to either BEP students for biotech centric classes or E & I students with entrepreneurship classes. E & I only have the seminar during core and the Silicon Valley trip all to their own. BEP only has a few of the HST classes to themselves. You can take up to 2 of the HST classes as well for electives as long as you meet the MBA requirements. Those in short are: required core (45 credits) with finance or marketing first semester (9 credits) followed by three semesters of a total of 144 MBA elective credits and that includes the 1st semester marketing or finance class. You can't take more than 54 credits a semester so this leaves you with 27 credits to work with. So, you could take two of the medical courses like hematology as well as cell and molecular immunology for 12 credits each, just an example. The only caveat with taking classes outside of Sloan is permission of the instructor, but I can't imagine unless the class was in high demand that you couldn't get a seat.
Cambridge is a mecca of VC and life science startups as well as established players like Novartis, Genzyme, etc. The opportunities are certainly there. I know BEP students getting into VC, McK's life science practice just to name a few. I have pretty good ties to the Sloan community currently and I'll let you know whatever else I find out.