Hello radiant glow,
Of the four communities that you are considering, I have experience living in the Philadelphia PA area. The cost of living for Philadelphia itself is significantly lower than for many other major US cities. I wasn’t sure if you were thinking of living within the city itself, or rather the suburbs referred to as the “Main Line,” which has a thriving Orthodox community (but can be quite expensive).
Having worked as a child advocate attorney for ten years in Philadelphia, I can tell you that it is in general a very violent and dangerous city, although the sections that you may be interested in (e.g., Old City, Center City) are relatively very safe, historic, and pleasant.
If you are considering the Main Line suburbs of Philadelphia, Bryn Mawr has the excellent Akiba Academy, now known as Jack M. Barrack Hebrew Academy. I frequently see many Orthodox families in this general vicinity, walking with ease to shul and other areas (shopping, public transportation, etc.). This location is very convenient and accessible by walking to anything you may need.
In the interest of full disclosure, I have to admit that I was born in Bryn Mawr and lived the first few years of my life in nearby Narberth, and I am extremely partial to this area! It is very safe and has incredible cultural opportunities. The Jewish community (of all denominations) is very large in the Main Line. Although you are interested in a religious school, it may interest you that the Lower Merion School District there is the absolute best in the state, due to the resources available in the Main Line. This fact may have some bearing on the special education services that are available, even for children in private school.
If you can give me an idea of where in the Philadelphia area you are looking at, I can give you more specific information.
I wish you the best of luck in finding the right fit in terms of communities for your family, and with your move!