Jiggy-Ninja:
4) Are you intending to transmit an analog or digital signal?A DDS chip like AD9850 that stowite suggested is not going to be useful for frequency modulation, only for frequency shift keying (or phase shift keying) of a binary digital signal. It will be pretty useless for analog modulation or demodulation. Modulation needs to be done with a voltage-controlled oscillator (VCO) and demodulation with a phase locked loop (PLL). PLLs have a VCO built into them, so you can more than likely use the same kind of chip on both the transmitter and receiver.
I found this article the other day ( All Digital FM modulation w/ Arduino & AD9850 – Zissis SV1RME Projects ) describing frequency modulation of a carrier with audio using an AD9850.
Until the OP comes back with the requested details then I can't say whether or not an AD9850 might help him.