Do the maxima and minima in the isothermal van der Waals gas model curves (P-V) below the critical point tell us anything physical?

Is there any physical meaning to the critical point?

What if I take 2 gases/vapors that do not react, where one is below the critical point and one is above and compress them to some pressure above which one phase begins to condense?  What are the pressures after compression? 

If I apply biaxial compression of 100 MPa on ice, what is the approximate vapor pressure? What is the precise vapor pressure?  What are the different wordings of this question asking about?

If I isothermally compress a vapor into a liquid, I have to do work.  What is that work equal to?  What is the associate P-V curve under equilibrium conditions?

How do you expect the Gibbs free energy of mixing to vary with composition?  Where is it maximum for a 3 component system?

Does the Gibbs free energy of mixing change with total pressure?  What is the influence of total pressure and where does that show up in the delta_G(mixing)?

Why do different materials have different P-V relationships (solid, liquid gas), what does this derive from physically?

For a certain volume and temperature, do you expect an ideal gas or a non-ideal gas to be at a higher pressure?  Why?

Plot a P-V phase diagram for some material, Plot the van der Waals gas equations from some material at different temperatures.  How are these related?

What would the P-V phase diagram look like if you had 2 gases one above the critical point and one below?