Answers based on my understanding as a foreigner with minimal understanding of the actual situation in Russia, but with desire to learn about it:
0. The value of a currency is more affected by expectations rather than actual economic variables. I have serious reasons to believe that the ruble now is facing a controled "speculative attack" orchestrated by all those that posses ruble globally. Who possess ruble globally: Russians and the buyers of russian gas. Also given that the expectations of the prospects of the Economy of Russia is based on the price of oil ... and the price of oil is controled by OPEC, i.e. Arab countries, permanent allies of USA. The depriciation of ruble is not a macroeconomic phenomenon based on how bad is entering Russia a financial crisis ... is just a political decision. Italy, Spain, UK, USA have much more serious economic problems than Russia.
1. The countries you mentioned are member of EU and NATO and have received serious subsidies and economic help. Just the agriculture sector of Greece has received since 1981 help about 5 billions euro. These countries cannot be compared with Russia, because they are protectorates of the Big Powers (new colonies). Russia is a sovereign independent coutry and should be compared only with the G20. Based on the G20 rates is about in the middle. Also Russia has become a "modern" capitalistic democracy in 1990. Greece is a democracy since 1848 (things cannot be compared). Also if we consider the Purhasing Power Parity and not the Nominal GDP, Russians have more power tha some of the countries you mention.
2. Russia is corrupted, but USA and China has biggest inequality on income based on the Gini Coefficient. Perhaps USA has more poor people per analogy of population than Russia. Also Russia is a massive country and this create serious problems to manage and control. Some oligarchs have personal armies in Russia ... what you expected. Russias spans from Europe to Japan. In its population are included many people that are not even Russians. Cyprus has a much bigger per capita income than Russia, but Cyprus is a small island in the size of the city of Krasnoda and for this reason is very easy to manage and control. Cyprus, Greece, Estonia etc are a semi-sovereign semi-independent countries ... Russia is an independent superpower. If Russia close the oil-pipes half Europe will remain without electricity.
3. Regarding Oil I don't have anything to comment. I totally agree. Russia is unfortunately massively based on oil revenues. This is normal. It has a comparative advantage on selling oil (Adam Smith, Ricardo David theories) ... so it does what it has the advantage to do. In addition... it has a massive industry. It is the biggest military equipment provider on the world. The 36% of the GDP is based on heavy industry (I think it ranks 8th globally). It is not just oil.
4. Regarding taxes. It is true that you have many off-shore companies, but at some point they will return back. They already started.
5. It is a historical fact that NATO and EU have expanded to East Europe. For me as an objective economist is an expansion ... for Russians is an invation. But only a naive person will think that NATO and EU didn't exploid the chaotic situation in Russia after 1989 to achieve this expansion. For Russians it doesn't make sense Russians to leave in a country, such as Latvia, that is a member of a coalition which was created with ONLY aim the destruction of Soviet Union, i.e. Russia. NATO is an anti-Russian coalition.
6. The ruble declines but at least in Russia they were not confiscated the 60% of the deposits as in Cyprus, which is a "proper civilized high-income european" country.
7. As an economist I recognise that some times dignity is more important than money. If Russians consider that they do anything they do (whether is called invasion in Georgia or invation in Ukraine) for dignity I respect this. If they do all this just to increase the money and power of some oligarchs, I feel sorry of them. But as I understood Russians consider that Crimea has always been part of Russia (if I am not wrong the majority of population there are Russians), as Greeks consider that Cyprus has always been part of Greece (80% Greek population). The difference that Greeks never had the balls to enter and take back Cyprus, but Russians had the balls to enter and take Crimea.
This is just a personal opinion. The fact that I am against wars it doesn't mean that I don't understand why countries make wars.
By the way, because I don't want to create the impression that I speak from a secure position.
The 35% of my incomes depend on Russian tourists and investors.
Also my country depends on Russia.
Due to the sactions and the decrease of ruble we all face serious economic problems.
Already many companies started to bankrupt.
As everyone else I try to understand the situation and have an objective opinion.
For this reason I encourage everyone to express his opinion.
Everyone is affected.