FWIW, your currently in the "Movie Mecca" industry of the world. There are tremendous opportunities for employment by casting companies that are constantly looking for new, and talented people in all aspect's of the movie business, including opportunities for musicians for movie scores. This not meant to derail your attempts in seeking what you come Hollywood to accomplish, just provide a little extra cash during the leans times, for beans and hopefully a little bacon, and or some funds to buy the needed equipment you are needing.
Casting agencies are always in needed of people, to fill in on sets on movie lots, as well location shots. People of all shapes, sizes, ages, and ethnicity's, for commercials, voice overs, crowd scenes, (people used as background shots called atmosphere shots, that are established in a public park, that are carefully choreographed, and controlled which at times are handled by second unit directors) and what ever.
Agencies are always loaded with a roll call of current work that is available of what they are looking for to place people to go location production's, dressed and ready to go using your inventory as to wardrobe department at a studio. If one is to sign on they will be (the agency) interested in every aspect of what you might be able to offer including props, that you might use as means to survive out in the real world. I your case a musical instrument may by be part of the roll call not to play, (or maybe to play but that also come under another union as well), just to be included in the scene with you. Any acting experience as well as musical background will a plus to increase employment opportunities.
The time spent and the wages very. Some times it can 4 to 6 hours a day ranging from $ 70. (non union) to $135. at current union scale union wage. If the set is all union that day you be unionized for the one days work and pay a small fee to the local as well what fees are collected by the agency. If you by chance are given a talking line for what ever reason the union will at this time ask if want to join, as talking lines continue to pay residuals every time it plays or airs where ever.
What is also a plus in this environment is that you will meet other musicians subsidizing there income for a little extra cash like yourself, until another playing gig comes along or to help with there educational pursuits.
There was once a time many moons ago that a friend and i (he was more into it then i, though as i always and had interest in Tinseltown and the movies industry) and we would go to locations shots in San Fransisco and see if the casting company needed any extras that day (back in the 70's). Sometimes we were lucky, other times we would stand the out skirts of the shot, trying to pick up some of the knowledge of the industry and watching them during production's.
There was one commercial i participated by chance. It was for car commercial. Having some JR. college drama experience i wasn't bashful and approached the film crew that day (making the commercial) and asked if they needed an extra for the day, and they did. There was an agency rep there on location and signed me right up. They were short as sometimes people don't make the location. I think i was there for about 3 hours, and in the final shot of the day i pulled a sort of Buster Keaton move and thought nothing of it just to do something different then the extras that i was working with. We got payed for that day and life goes on. Then a 2 month's later i remember i received another 2 checks in the mail form the casting agency totaling about $300 or $600 dollars, as they ended up show that commercial a number times in the north east.
If your interested i have included a a site for that area http://www.extra-casting.com On this page you find a tremendous amount of information of what is expected of you to be added on there rosters, as well as pertinent, valuable, information on guidelines and etiquette.
Remember this Tinseltown and you have to mange yourself, but that doesn't mean to prostitute your goals or self respect but just being honest with your agency.
Never Surrender Never Give Up, and as as everyone has expressed, Good Luck.