| would suggest you start in small blocks, and work from there.
First off, as you're using a small PIC, I would suggest you allocate an unused pin as RS232, add a MAX232 (as my tutorial), and practice sending data from the PIC to your PC. This is basically to give you easy debugging, as you can send output directly to the PC screen.
Then add A2D routines, and send the data out to the PC over RS232, again my tutorials include all the parts you need, but need very slight changes for the 12F675 due to it's limitations.
Once you've got all that working flawlessly, then you can start worrying about the RF side - first off decide how big your packets need to be, this depends if you're sending ASCII or binary data. Again, my tutorials provide all the bits you need, just a few changes, and 'stick' the different bits together.