The people here are very friendly. They just tried their best to help you. Please don't feel disappointed or frustrated, if you didn't get the answer you had expected. Back to your concerns, I don't know which schools are easier to get in in terms of Linguistics program. But in my very personal opinions, the following schools are relatively harder to get in: MIT, Penn, Stanford, UM Amherst, U Maryland, Berkeley and UCLA (as you have already mentioned), Harvard, and Cornell. I am not discouraging from applying to these schools, just trying to answer your questions.
From your description, I guess your studies will be fully funded by the school you are working for right now. In this case, you can apply to some state universities that enjoy a big reputation in Linguistics but can afford to fund every student. Schools like Arizona State, UC Boulder, Rutgers, South Carolina, Michigan State, Delaware, Oregon, Kansas might be the ones you are trying to look for. Tell them that you have outside funding resources when you are doing the online application.
In terms of the length of a program, it mostly depends on how your research is going and your own abilities. If you have the ability to finish it in four years or even there years, no body in the department will give you a hard time on that as alone as you can pass your dissertation defense. I hope my post can be helpful to you.
Good luck.