Btw how politically legitimate is the vote on firing their own president, according to Ukraine law?
I think it's possible in most of countries around the world. It's called impeachment. Also now I'm concerned about the eastern part of Ukraine. President had the biggest electorate there and his team still has the power there. Some of them tried to announce, first, the independence and, second, become the part of Russian Federation (and that makes no sense, how can you become independent and instantly join Russian Federation?), SBU (the same as CIA in US) instantly reacted on this and today they (team of Yanukovych on the east) announced the completely opposite: they want to stay as a solid government like it's written in Constitution. Thus, eastern Ukraine is pretty much getting steamrolled with protesters and president's team there starts losing their powers. But I'm still concerned more about Crimea. There are a lot of Russians there (mostly families of current and former Russian navy militarists). There is a base of Russian fleet right in Crimea, this was also a big problem for Ukraine as the Constitution of Ukraine forbids to have any foreign military forces on the Ukrainian territory but due to contract Ukraine couldn't throw them out, so Ukraine was just waiting for it to end. Unfortunately, Yanukovych was a President by the moment the contract reached the ending date, what he did is simply a betrayal of Ukrainian people and a step against the Constitution - he prolonged it for 40 more years. Russia knows that if the new government comes - Russian navy forces will be asked to leave Crimea that will lead Russia to lose the control of Black Sea. They will find any excuse to fight over the Crimea just to save forces there or even annex it. As I've said, there are a lot of Russians in Crimea (and a lot of them have Russian citizenship which is forbidden by the law of Ukraine) and I guess it will be used as a main excuse to involve Russian military forces. The biggest problem is that people of Crimea will mostly support this as Russia is their original motherland and their families work for Russian military forces.
Basically, Crimea is a weak spot of Ukraine. But I really doubt that Russia is ready for actions in Crimea so I guess they'll just leave it as it is.