Your first problem is, you can take the courses and pass the salesperson's tests, but you absolutely cannot be licensed without a sponsoring broker who "holds" your license and supervises your real estate activity.
This means you need to work for a firm on some level, you cannot work independently. Your right to receive commissions from your sponsoring broker--the only legal way you can get paid--does not exist unless you have a sponsoring broker.
Secondly, many brokerages will expect a percentage of any of your own property that you sell. Yes, you read that right. You will have to pay your broker of record a cut if you sell your own property while being an agent of that broker. At some firms the cut is large.
I'm not at all sure you will save money when you sell because you are an agent of some brokerage firm. As an agent I have represented real estate licensees who felt they were better off hiring my firm and me than negotiating for themselves, a task that is really not for everyone.
Many sponsoring brokers will not accept you given what you are planning. In fact, sponsoring brokers expect you to make money for them, and some will pressure you to get listings and show property. There are other brokerage firms where you can pay a monthly fee and they will let you work part-time, but the fees can be high. With your schedule, I seriously doubt you have enough time and schedule flexibility to be productive at all as a real estate agent.
My advice is this: Take the classes in person at the Real Estate Board of New York's offices (east Midtown Manhattan) so you get a great education at a great price; take the classroom test and the $15 licensing test; and then put your records away. Your classroom work is valid for years (check with REBNY to find out how many years), you can always get a sponsoring broker later.
My further advice is, do NOT take on-line coursework for a license! I can't emphasize this enough. Your goal is to learn, not just to get a license, and you will learn much, much more, insider info, and make valuable contacts, if you study in a classroom setting.
Lic. Real Estate Salesperson
Charles Rutenberg LLC