1) According to the information provided by the traffic controller on the ground and regardless of the fog, this should have been a routine landing. Planes land without an incident in such, or worst conditions each and every day.
Its not routine to land at a military airport without navigation aids to allow landing in bad weather. Minimum visibility to land was 1000m - it was between 150m and 400m when they attempted to land
2) The Polish crew was top notch. You don't get to fly the presidential plane unless you are absolutely best at what you do.
Maybe but they were flying a aircraft where the options to get a lot of experience was limited. They had a lot of experience considering the aircraft type, but they had very little experience compared to most commercial flights. Basically they were relatively in-experienced less than 2000hours versus 20,000 hours for many commercial pilots.
2) Anyone with even a rudimentary knowledge of geopolitics and/or linguistics will tell you that Polish pilots do speak Russian very well. If anything else, the Russian numbers were certainly NOT of any challenge to them, and most certainly were not, as described by the air traffic controller a "black magic" to the crew.
To fly the 154 requires Russian language proficiency - its part of the training. So yes they must have been proficient in Russian.
3) The instrumentation on that plane was labeled in Russian - wouldn't you think that you have to know the language in order to read the instruments?
4) A descend path of any landing plane is based on its calculated ALTITUDE
Do you mean altitude relative to the airport, or sea level? And it depends on air pressure which varies with the weather. Russia uses a different system for altitude to some countries. This is potentially a source of confusion.
5) The plane landed or was guided by an air traffic controller who DID NOT know (and admitted to it) what the altitude of the plane that was landing was.
The pilot flies the aircraft, not ATC. The airport wasn't equipped to give altitude information - which is reason why they suggested diverting. The 154 pilot stop providing altitude information to ATC which made their further assistance impossible.