Do I have to get a masters in my major field to get a job?

Hi! This is a great question, and the answer is different depending on what you would like to do. In general, biomedical engineering is a great foundation for a number of related and/or interdisciplinary engineering paths. However, industry often has trouble determining what positions are suitable for biomedical engineers. Universities will emphasize different engineering disciplines in their Biomedical Engineering program, making the graduates very diverse in their expertise. A great way to supplement a biomedical undergraduate degree is a minor/concentration in another subject, such as biology or nanotechnology. Additionally, a masters degree in a related field of concentration would be a great way to focus your expertise. In my personal opinion, a Masters in biomedical engineering on top of an undergraduate degree would not actually be much more helpful in finding a god job. Masters degrees in general take around two years, but there are some universities that offer a masters degree in addition to the Bachelors for only one extra year if this is a path you want to take. To find a job with just a Bachelors in Biomed might be a bit challenging, but if you distinguish your expertise well on your resume, it should not be too difficult. Some great ways to help yourself stand out is a minor, an internship, research, etc.
In your case, if you know you would like to go into the pharmaceuticals industry, a chemical engineering degree might be better suited for you than a broad biomedical engineering degree. 
As far as starting your own company, I don't think extra degrees are required as long as you have the appropriate expertise or have the appropriate partners. If you are particularly interested in the startup biomedical world in general, I would suggest a Bachelors in Biomed and a Masters in Business as a good combination.

Good luck!