Small Observation on E-fighting Styles
Though the concept is the same, the styles of energy fighting is very different between planes. In relation to the questions in the original post, this means E fighting tactics on the critical pass differs between planes.
I haven't much experience in the P-51s, but generally, the P-51D and Bf 109G-10 seems to represent the two different types of E-fighting styles.
In the pure sense as a aggresive hunter-killer fighter, P-51D has most of the attributes needed: it is fast, very high maximum dive speed, good high speed control(aileron/elevator authority, good instantaneous turns, and armed with high velocity/accurate weapons.
On the other hand, the Bf 109G-10 seems to me more of a 'defensive' E fighter. This is probably mainly due to its actual historical role and circumstances. It is fast, dives good but horrible high speed control, but what it lacks in control it makes up with astounding ability to climb.
As a result, P-51s on their first diving pass usually seem to drop from directly above.

No doubt they have the ability to do so, and since its high speed handling is pleasant while rate of climb not very impressing, they use every ounce of energy gained on the "Boom" maneuver and directly turn it into a "Zoom" maneuver after the pass is done. I don't think I've seen many P-51s (good stick or bad alike)doing a low-6 pass on their first attack. Usually when I meet a P-51 they seem to come in from the 'traditional' high-6 angles.
In contrast, Bf 109G-10s have horrible high speed handling. The energy gained during the dive cannot exceed 450mph, or you are in for one nasty trimming frenzy. As a result, the first attacking pass of 109s come usually from low-6 angles. Whatever dive they do they fall under the target plane, regain flight control by blowing off excessive speed in a shallow climb as they approach the target from low-6.
For the P-51D, the "Boom" part of the manuever is directly connected to the attack. In the 109G-10, the attack comes right before the "Zoom" part.
I am not suggesting more skill is needed to fly either P-51 or the 109G-10 (depending on the preference of the reader

), just pointing out from my personal experience that the attacking styles seem to differ a lot(well.. I do admit its not that long an experience..

). Of course, this is a general observation, and in some cases a 109 may do a attack from high-6, or vice versa with P-51, but the general characteristics of the plane seems to dictate the style of E fighting in the more typical/usual cases.
Another interesting example is how typically Japanese pilots like Mitsu or Blade use Spitfires or N1K2s as an E-fighter. In these planes, the general speed is not sufficiently high enough to provide 'lazy' E-fighting styles, and as much it is easier to chase down the enemy toe-to-toe in these planes, it is also easier to be shot down by planes of simular types by overwhelming odds after the chase is done.
Their style of E-fighting seem to be very instinctive. At the first sight, they dive down steep angles without hesitation(pilots in the more orthodox E fighting planes such as P-51s, Fw 190s or Bf 109s etc.. generally seem to take up some time planning their move).
Since those planes are very maneuverable in the turning sense, if the circumstances permit, after the "Boom" part they blow E off very suddenly by wild-but-logical maneuvers, and situate themselves behind the target. They change the fight suddenly from "BnZ" to "TnB". In this case, the Energy is used as sort of a 'boost' to get themselves behind enemy planes they normally wouldn't be able to in a co-E co-alt situation. E-fighting for (relatively) low-speed highly maneuverable planes usually take it in this style.
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Just thought it'd help to post if somebody didn't know about my little persoanl observation
ps) And everything in this post is empirical. I'm sure there are other pilots who have different things to say

Carry on guyz.