You should clear these warrants up as soon as possible, if you're pulled over by a cop you're liable to be arrested with warrants floating out there. Your best bet is to hire an attorney that can handle these warrants easier than you'll be able to yourself. If you absolutely can't hire an attorney, you can calendar these matters yourself by going to the clerk. The judge could remand you into custody when you show up to court (depending on the nature of the charge(s) and how old the warrant is) but this is doubtful. It's even more doubtful if you have an attorney handle this for you. Best of luck.
It is possible that you can resolve all of your open cases without doing any jail time; however, it would be dependent on the facts involved. You can hire an attorney that can handle the whole matter for you without you ever needing to step foot in the courthouse. You will find many competent attorneys on this website, most of whom will provide you with a free consultation - they can discuss the facts of your case(s) and provided you with your options.
This answer is for general informational purposes only and shall not constitute legal advice. I have answered a question on a public forum which does not establish any attorney-client relationship. For a more detailed legal analysis you should consult with a legal professional in your area.
The MTA riding without a pass was likely bumped up to a Misdemeanor. The FTA is a misdemeanor. You should secure the services of an attorney to make sure that you do not serve any time in jail. These can likely be brought back down to infractions with the proper approach. Give me a call to discuss your case.
Seth Weinstein, Esq.
Southern California Criminal Defense Attorney
This reply should NOT be considered a legal opinion of your case / inquiry. At this time I do not have sufficient factual/legal documentation to give a complete answer to your question and there may be more to the issues you raised then I have set out in my brief reply.