I think UC's are more competitive than the rankings suggest. If you are interested in Biostats because you're more drawn to applied research, UCSC and UCSB are also great choices. I also believe UC Davis allows you to apply to both Stats & Biostats. Since the departments share professors & the courses, I'd suggest applying to both if you really want to go to Davis.
Given your mathematical background, I really think you will have somewhere to go to. My mathbackground is much inferior and I got into 3 places last year.
I think your targets are reasonable but not guaranteed, and agreed about Alabama-Birmingham being at the safety level (though I hesitate to call any program safe). Drexel is closer to UAB than the other programs, though, so not sure why you have it in the "reach" category.
