Hi, Ashley! I am currently employed as a full-time sonographer that performs ob/gyn, abd, vascular and echo. I can't answer all your questions, but I'll try to answer some of them.
First off, don't let anyone stop you from doing what you want to do. You are the one that has to do it for the next 40 years, not anybody else. If you want to work in the medical field, work in the medical field.
I don't know about Sanford Brown in NY, but I do know that it is expensive and that it is not as well respected as other programs. It is very much a for profit institute and I would be weary. Community college programs are a great option and that is what I did after making a career change. It's not nearly as expensive as a private four-year but can still cost quite a bit. One important thing to look for in a school is that it supplies you with a clinical site. Some schools require you to find your own which can be very difficult. Also, although you will already have your Bachelor's degree, I would still recommend finding a school that is accredited by the CAAHEP. You can sit for your boards with a Bachelor's, but an accredited program ensures that the program you are entering must meet certain criteria that makes it more likely you will be entering a quality program. Program length can vary, but is typically 15-24 months, although some colleges are offering Bachelor's degrees.
Songraphers and ultrasound technicians are typically the same. People who do ultrasound prefer to be called sonographers, as they feel being called technician somehow diminishes what they do, as in nail technicians do nails and I provide an important medical imaging test and provide an interpretation of the test to the reading physician. However, the terms are pretty much interchangeable when it comes to looking for a job. Also, all the professional associtation use the term sonographer.