Hi Phil.
I guess the answer to your question about the RF receiver is: neither will work because of the frequency. You could try replacing the crystal though, in that case I would buy the more expensive one, since the price difference is only 1$.
This is the IR Receiver Module I'm using: http://www.everlight.com/upload/product_pdf/IRM_3640N3.pdf.
You should buy one with some internal circuitry. I guess the closest you get to what I'm using at Sparkfun are:
IR Receiver - TSOP85 - SEN-08545 - SparkFun Electronics or SparkFun IR Receiver Breakout - TSOP85 - SEN-08554 - SparkFun Electronics.
My libraries don't support RF transmission. But it shouldn't be to hard to re-write the RF receiver library to support transmission as well. You would need a 310MHz transmitter though. Or you could use the playground lib for the CM17A that BroHogan mentioned.
Love your iPhone app, that's really cool! I have a Samsung Galaxy S and want to try to write something like that.
-Thomas