Basic Aerodynamic equations

In answer to your queries: 

Question 1

Engine Net Thrust = Mass Flow of Air x (Jet Velocity - Speed of Aircraft)

Points to note : 1.  You have to use mass flow not volume flow, as the former
is constant through the engine, but the latter varies with pressure which is
higher in the jet than the intake.

2.  You must take account of the entry momentum of the air as well as the exit
momentum.

Question 2

Force on a plate perpendicular to a flow could be thought of as stagnation
pressure on one side p + 0.5 x density x velocity squared and static pressure
on the back.  This gives a nett force of  0.5 x density x velocity squared x
area or a drag coefficient of 1.

That, however, is a gross simplification, which ignores the effects of
compressibility and viscosity

Question 3

I need to refresh my memory on this one

If you are interested in this subject I suggest you get a book on an
Introduction to the Physics of Flight.

Gerald Wilson