How its work
And what elements who change the gain of this oscillator
And what elements who change the frequency
And what is the condition oscillation of this circuit
How its work
And what elements who change the gain of this oscillator
And what elements who change the frequency
And what is the condition oscillation of this circuit
The condition of oscillation is a general condition. It does not depend on the specific circuit topology.
If you want to analyze and/or construct an oscillator the first task is to understand WHY and under which conditions a system is able to oscillate.
These fundamental things cannot and should not be explained in a forum like this.