I think that the West was surprised by the calm reaction of the Russian banking system to the SWIFT disconnection
Well the plans were in motion for at least 8 years, need I remind you of Crimea annexation?
It turned out that the banking system of Russia is perhaps the most progressive in the world, without problems with legacy, mainframes, punched cards and cobols - flexible, manageable and easily customizable.
I'm not sure what you mean here, Russian banking system is just as bad as anybody else's. But the reasons why sanctions had a reverse effect was firstly because they were mostly jokes and also because Russia simply joined the multi trillion dollar economical infrastructure built and perfected over the past 43 years by the most sanctioned country in history Iran that is currently sitting among the 10 largest economies in the world (or 20 largest according to World's Bank).
They didn't really do much, they just hopped from one train to another while Europe keeps pumping Ruble's value and any imports that were stopped got replaced by competitors at cheaper prices with higher qualities!
But the gas pipeline has a valve that can be easily closed.
It can be closed but it can't be opened more than it already is.
Europe froze Russia's money, which she paid for gas supplies, that is, Europe actually received gas from Russia for free.
Last I heard it was a total of $5 billion Russian assets that were seized in which case Russia responded by seizing $500 billion Western investment in their country so by your logic EU is paying 100x for the gas.