Uwe, Please, allow me to share some results.
1. MiKTeX placement on a D-partition. -- I was barking up the wrong tree. MiKTeX worked fine in this configuration. No problems with updating. 2. New package installation. -- I "installed" the font packages using the "MiKTeX Package Manager". But then I was supposed to "Update the file name data base" and to "Update all format files" in the "MiKTeX Options (Admin) > General" dialog. Initially, I overlooked that. Now I did it. Perhaps, you'll save a score of other chaps by reminding them about that point in your http://wiki.lyx.org/Windows/Cyrillic 3. Non-default fonts. -- I could swear your sample LyX was still producing a bitmapped Russian on my system, even after I corrected my error in the installation of new latex fonts. But then I tried a Latin Modern Roman (perhaps, a T2A encoding, too, can't be sure anymore). That produced the vector fonts, for a first time. After that, I could revert back to your original settings, all defaults. Now the bitmapped fonts were gone for good. So, it appears that there was an "on-the-fly" change in the font configuration. Behind the scenes. (Not controlled by my Latex code anymore. But I am grateful for this outcome). I am not sure whether the remaining questions are a legitimate followup or a separate entry. But I'll dare to ask. 4. Font change. -- Suppose I need to switch between several different font designs in the body of a document (say, between "Latin Modern" and "Palatino"). What are the Latex commands? 5. Latex font names. -- How can I learn which fonts are available on my system and what are their "Latex" names which can be used in these commands? 6. Character sets in the fonts -- How can I learn which symbols are available in which fonts? 7. Settings combinations -- How can I learn legitimate combinations of input encodings, font encodings and font names? Once again, you saved me a lot of frustration, thank you. Best regards, Leonid.