What makes you believe your layoff was connected to using FMLA the year before? You can't be terminated/laid off just for using FMLA but you can be terminated/laid off if you would have been terminated/laid off had you not used FMLA.
They don't have to keep the employees that have been there the longest unless it is noted/stated is a binding employment contract or CBA.
You just can't be discriminated against due to a reason prohibited by law (examples religion,gender, race......).
File for unemployment ins. - the state will decide if you qualify. Based on what you posted, you should.