you can remove R1 if not using an electret mic but wouldnt that feed the supply voltage directly into the mic element ?
Remove R1, not replace it with a short
Also i would like to add a gain control, where would the best place for it be and would it be in series
or taking the signal down to ground ?
Do it after your amplifier, with a log-taper pot, rather than varying the gain.
And lastly would i be better off using an op am than a transistor amp ?
Define better. Find an opamp with a 300 MHz GBW product for $0.15
Though you only need about 20MHz of that to get from 1.5mV, to 1.5v at 20khz bandwidth. (though I suspect you wont need that much for your radio)
Either way I suspect the simple class A amp will suffice as long as your mic isnt too far away from the preamp. (with the circuit ground referenced the way it is the common-mode rejection of the mic wont be great)