@I_Hate_Infinity
I'm late to the thread and (1) has already been covered, the short version of which is that the moon's orbit around us is elliptical *and* the earth's orbit around the sun is elliptical so, if earth is closer to the sun and the moon is at its furthest from us, the eclipse will be of the 'annular' type.
Even then, the alignments have to be just right: the moon's orbit is tilted, relative to earth's path around the sun, making partial eclipses more common and, when it is a partial, there is no way for the layperson to assess that it might have been annular, or full, or "over-full", from a more advantageous viewpoint (which would have to be off-planet).
(2) The thing which makes a bell, a vibrating string or other resonating object decay to nothing, on earth is the air around it. In conducting sound waves away, it removes vibrational energy. Earthquake vibrations can be detected thousands of miles away but, ultimately, are absorbed by what they travel through. Mantle rock is supposed to be soft and gooey; ideal for sound absorption. The oceans could absorb some too.
The moon, by contrast has no molten core, no 'gooey' mantle; it is solid right the way through. There is no ocean or atmosphere to transmit sound and the vacuum of space will not conduct vibrational energy away, either. This is the conventional explanation of why it rings like a bell, when impacted. You've undoubtedly read this and, whilst it's none of my business, I'm curious about why you find this explanation inadequate?
I haven't fully addressed the issue of lunar surface dust, which, in jiggling around, should dissipate vibrational energy, almost like a liquid. The tests showed ringing did decay, eventually, so some internal dissipation is going on.
(3) No mining has been done on the moon, so we've only sampled the surface. For starters, the remnant of the "Thea" impactor may have completely liquified. Heavier elements, like iron would have sunk, to form a core. Titanium has a lower density and would have floated to the upper layers - a sort of 'fractionation' occurs, in much the same way that inner planets are more rock than gas and outer planets are more gas than rock.
You would also expect the last of the debris, from the Thea impact, to fall back to the moon's surface to be the less dense material. The moon became techtonically inert, whilst the earth has subduction zones; for every mil that the Atlantic is wide, a similar amount of Pacific ocean floor has been shoved into the depths. The earth's surface has been churned up so surface minerals are a varied mix.
Additionally, an impact on the moon would send rock debris and dust and huge distances because of the lower gravity and the complete absence of air resistance. A succession of impacts would mean that materials would spread over the surface giving a very uniform blend, such that multiple sampling sites, of the various moon missions all get similar mineral mixtures.
Carl Sagan's Cosmos series featured the account of a 12th/13th century monk who observed a bright flash at the edge of the moon, followed by a bright plume, becoming a detached crescent, then a fogging of the surface, lasting some hours. A convincing description of an impact.
Oddly, I have not seen this story mentioned again in the 30-odd years since that series was first broadcast. It may have been discredited by referencing astronomical archives from other parts of the world for the claimed date, which were not available when the series was made.