Elena,
If you're not a legal resident of the US, then you need a J1 to work as a flight instructor - which means the only choice you have to make is HAI or Hillsboro. (they're the only ones that can issue J1 as far as I know)
Sign up for the Private course and enter the country on an M1 visa.
Once your 6 months is up, apply for change of status to J1 (wave money under thier noses...) This will give you another 24 months (plus processing time) Now you can concentrate on getting trained and getting a job.
I agree with steve76: The most important thing is to try to get hired at a school which also does commercial work, flies bigger ships etc. Obviously as a new CFI, you'll go and work for the first person that hires you, but don't stop looking. I was hired as a CFI, but after a while a commercial position came up - as I worked for them already, they hired me. If you go to a company which just does flight training, the step to commercial flying is much harder.
Its a long road, but fun.
Good luck!