Hi Ivy -
From my experience, the job market right now is great, and is expected to stay that way. There is growing demand for the services of LA's, but the number of graduates that schools are producing is staying level (for many reasons) - it stands to reason that growing demand & static supply will further increase the opportunity and perhaps wages.
Given your interest, I think landscape architecture might be a good fit for you. There's a growing realization of the impact the designed environment on people's health, and a number of LA's are specializing in healing gardens and other health-related issues.
As to getting into school, I can't really help you much on advice - I went into my BLA straight from high school, and my entrance into an MLA program was heavily weighted by my BLA, 10 years of experience, and license. Your best bet would be to visit several MLA programs and talk to the faculty and students. See the Amer. Soc. of Landscape Arch's website -
www.asla.org - for the best listing of accredited MLA programs.
In NY, Cornell has a great reputation, but SUNY @ Syracuse has an accredited MLA program as well.
Again, I'm happy to answer any questions.
Brian