Re: wireless circuit
90dB of audio dynamic range will be very difficult to do and you will only get that when you have a strong rf signal reaching the receiver and low interference.
You need to descide if it is going to be manually tuned, crystal controlled or synthersized.
If you have a license for a paticular frequency then you will need to be very close to the correct frequency, perhaps +/- 1KHz. In that case you need either a crystal controlled transmitter or a frequency synthersizer.
If you make it manually tuned (LC oscillator) then you will have to consider frequency stablility with temperature, supply voltage and time.
There are lots of books about superhetrodyne radio receivers.
Added after 10 minutes:
Depending on your application it might be acceptable to put a compressor on the audio input.