I just disagree with your assertion that minimum sink = maximum lift.
3.) Smallest descent angle yields biggest possible value for lift in the equation L=W Cos (Angle Of Descent.)
Could you clarify which of points 1, 2 or 3 you feel is invalid
Not invalid, just misinterpreted... You have to consider descent RATE as well as ANGLE.
Using your same equation, note that weight is constant, while lift and descent angle are varied with airspeed.
When airspeed is decreased from L/D max to max lift (stall), L increases. So, for a constant weight the ANGLE of descent will indeed increase. However, the sine of the descent angle is defined as the vertical speed divided by the airspeed. If airspeed is decreased sufficiently, even a slight increase in descent angle will result in a lesser vertical speed.
For example, assume a glider has an L/D max speed of 45 knots (4557 fpm), and a min sink speed of 300 fpm at 40 knots (4051 fpm). [Note: These are not "real" numbers, but are in the ballpark for a low-performance glider like an SGS 2-33.] At min sink speed the descent angle is 4.24 degrees -- arcsin 300/4051. Now assume that at 45 knots (L/D max) the sink speed is 325 fpm. The descent ANGLE will be only 4.09 degrees -- arcsin 325/4557 -- even though the descent RATE is greater!
Note that the descent rate at 45 knots will have to be 337 fpm to equal the descent angle at min sink speed. The situation satisfies your equation.