Look up Bridge Programs. They give you a Masters Degree and if you do well 9/10 they will automatically accept you into medical school! They take MCAT scores. Even though it's not a post bacc program, maybe it will help you in another way. Never give up hope! Good luck!
1) For the vast majority of people, the MCAT is much harder than the GRE. With the MCAT, you're competing against an extremely bright pool of people who are heavily invested in the test. The MCAT has far higher stakes than the GRE because it is weighted more heavily. Medical school is harder to get into than most graduate schools in general. With the amount of preparation required to do decently on the MCAT, you could do extraordinarily well on the GRE.
2) Yes, there many programs that accept the MCAT rather than the GRE. They are called Special Masters Programs, or SMPs. They include University of Cincinnati, Georgetown, Tufts MBS, RFU, and Drexel.