I think I understand FSK pretty well. The idea is to create/receive a set of two frequencies on a specific time frame. If I get say 10 rising edges in my time frame, then it is a 1. If I get half, or 5, then the frequency is half and so it is a zero. There are a lot of difficulties in implementing this with my inexperience.

For one, how do I use the PCA counters for receiving on edge triggered? It may even be easier to do both edges.
Second, I need to compare the value in the counter and assign a binary 1 or 0.
Third, I need an algorithm for sending start/stop bits, and perhaps even a model similar to UART for sending a byte.
Fourth, I need to have an ACK byte to make sure I received what I wanted. This same ACK byte is sent and received depending on the scenario. Although for my purposes, I really only need to receive an ACK byte because I will be using the microcontroller to send varying FSK data, but will for now only receive an ACK, and it will be the same ACK.
Fifth, PCA frequency output is a sqare wave. Do I have to do any modeling to it to get closer to sine or should a sqare wave suffice?

So now that I have a better overview of it, I think I need to start with sample edge triggered receiving code for PCA. I'm still searching with Google, but if you happen to find some examples, please post a link.

Thanks for the help and the reply!