Clarification about P1 dB Compression Point and How to draw it

I have following clarification about P1 dB compression point

(1) What is the significance of P1 dB compression for the design of low noise Amplifier.
(2) What message P1dB compression point conveys to us.
(3) What is its importance in the design of Low noise amplifier.
(4) P1 dB compression point, how it is different from Third order intercept point (IIP3) and third order output intercept point (OIP3).
(5) In the screen shot diagram2, it says that P1 dB compression point at 2.45 GHz is 8.5 dBm output power. What message it conveys for us design of low noise amplifier.

How to draw the P1 dB compression, while taking Input power versus Output power and fundamental power. How we have to take P1 dB compression point 1 dB down from the linear to nonlinear.
Below screen shots shows the P1 dB compression point drawn diagram. How we have to take 1dB down as shown from the red ring in the screen shots.

1, LNA = Low noise amplifier, input level = -120 -> -90 dBm, so it is unlikely that it would have enough gain to reach its compression point. Its design would be to maximise gain and minimise noise.
2. 1dB compression point is a useful rating to compare different amplifiers. It does also equate to a certain level of IP3. Can't remember what the magic number is (40 years since I went to college). A low level IP3 is only important for linear amplification, for narrow band CW, it has no relevance.
5. Nothing to do with low noise, just its linear power output .
Frank

Hi chuckey,
What you said in the posting # 2 , I totally didn't understand. Some can clarify my clarifications in the posting #1.