Reliable wireless data transfer

[dhouston]

Would you suggest specific oscillator settings ? Eg. External 4,8 or 20MHZ or would it be at all possible using the internal oscialltor?

I almost always use the internal oscillator.

Any particular pin choices for TX on the transmitter side and RX on the receiver side ?

Any pin, except for MCLR, should be OK. It really depends more on what other functions you want the PIC to handle.

Almost all the transmitters are SAW controlled so their frequency is independent of the PIC and most protocols can tolerate ±10-20 variation in pulse/space durations