Most Russian gas is sold under price formulas directly linked to oil products (diesel and fuel oil), usually using an average over several months. Thus Russian gas prices tend to follow oil prices with a lag of a few months and with much less volatility.

In the long run, we're all dead. John Maynard Keynes

The Nabucco pipeline is supposed to be built from Turkey to Austria (via Bulgaria Romania and Hungary - not sure abotu Greece but I think not). This will indeed allow in the long run to bring gas form the Caspain and Iran to Europe, but do note that most of the gas currently in Turkey comes from Russia, so it might yet be turned into an additional route for Russian gas... - it will certainly allow for swaps with the Russians)

It's well on its way, I think, and could be ready in a few years.

In the long run, we're all dead. John Maynard Keynes