Questions about very basic RF circuits

Could you please answer some questions about an AM Transmitter and Receiver circuit I found?
The first one is the Transmitter, you can go to 0:22 to see the circuit diagram:

http://www.youtube.com/watch?v=_4-Sx-T6VBc

What does the Oscillator Chip do exactly? I know it should mix the Audio Signal with the Carrier Wave. Is this a complex process or is it very simple? I would like to know what happens inside it or at least have the equivalent circuit diagram.

The second one is the Receiver, go to 0:26 for the circuit diagram:

http://www.youtube.com/watch?v=VqdcU9ULAlA

My question is: if I substitute the DIY capacitor and inductor with commercial ones, with a fixed value, would the circuit work the same? Of course I wont be able to select different frequencies, but would it work properly?

My last question is: with this super-simple Transmitter-Receiver system will I be able to reach a communication distance of some meters, if I use big antennas and good signal amplification on the Receiver?

Thanks a lot to anybody will help

The oscillator is a precision 1 MHZ crystal controlled one. What they are doing to AMPLITUDE modulate it, is to feed the audio in series with the power feed to it. So the audio adds/subtracts from the power voltage and so increases/decreases the RF out put. This is not a very effective way modulating the RF, because the oscillator might not reduce its output until the voltage falls to 6V, but increases the RF output straight from 9V.
The 1 MHZ signal falls in the medium waveband at 300 metres.
Frank