I believe your plots are reversed. The top plot is the closed-loop response (but of the whole amplifier, including the input blocking cap). The second plot is the open-loop response -- and you should extend the frequency range to catch the point where the gain is 0dB, so you can see the phase at that point.
Note that this has been corrected -- see "Update 3", above.
You are looking for (and trying to avoid) the point where the open-loop gain is equal to exactly 1* -- this is the point in the second plot where the amplitude of the gain is 0dB (0dB = 1) and the phase is 0 degrees.
Your gain margin is the amount the gain would have to change at at 0 degrees of phase shift to get 0dB of gain (i.e., loop gain = 1). Your phase margin is the amount the phase would have to change at 0dB of amplitude gain to get 0 degrees of phase shift (again, loop gain = 1).
From the OP: "For 0db gain, phase is 41° (1.77MHz) and for phase 0°C, gain is -6.51 dB (3.16MHz)." This means that the phase margin is 41 degrees (which is a bit tight -- 60 degrees is generally considered safe for control systems involving mechanical parts) and 6.5dB (which is fine in almost anyone's book).
* Note that this whole "loop gain = 1" thing can get confusing, because in most control systems analysis, there's a summing junction in the loop that isn't taken into account in the analysis -- in that circumstance it's a "loop gain" of -1 that you're trying to avoid, not loop gain = 1.