Hmm. I'll take a stab here. Yes, there is A TTL exposure meter in the MP, but not TTL flash metering (the M7 has both). The "MP finder" refers to the internal improvements they made in the finder vs. the older M6 style, which suffered more from flare. The new improved finders have a condenser in them to reduce this problem; all new Leicas now have this improved finder. This fix was introduced with the MP, and is called the MP finder. To avoid this sort of confusion, it should just be called the improved finder, but whatever.
The optical reader is, I assume, the reader built into the M7 to allow the camera to automatically read the film speed off of DX coded film cassettes; the MP doesn't have DX coding (you need to manually select the proper film speed on the back to ensure proper metering). As for how robust modern Leicas are compared to the classic M2/3's you are used to, well, they still very well built- but have lost just a touch of the old "feel" they had, due to hand-built construction. They are still very solid, feel excellent, and are quite robust. .58 refers to finder magnification. Leica now makes three different finder magnifications: .72 is the tried and true magnification all Leicas have had since the M2, until they introduced a higher .85 magnification option near the end of the M6 run. They then brought out a "wide angle" .58 magnification option which is especially popular with eyeglass wearers and real wide angle lovers. The M3 had a .91 finder magnification, just for reference.
Hope this helps.
