With regards to your second point, would you view the 2nd Chinese/Russian oil deal as China directly hedging against such a possibility at least in terms of energy (however unlikely)?
I've been arguing for some time that this was an opportunistic deal for China, not one that was critical for it. China and Russia had been negotiating for years on price, and it's not coincidence that suddenly there was movement in the deal in the wake of the Crimea sanctions. It's not unreasonable to make an educated guess that China was able to exploit Russia's desperation in order to negotiate a good price. Until we have the details (and we may never have the details), we'll never know for sure.
But there is one other factor, about which I've been pounding the table incessantly on PDF: China simply doesn't need Russian energy, and is already extremely well diversified, which provides it with even more negotiating leverage. Do you think Saudi Arabia, Angola, Iran, Oman, Iraq, etc. would feel bound by any US sanctions against China, when China is such a major source of revenue for them? Yeah, I didn't think so, either. And with the Silk Road 2.0 project, a naval blockade becomes even less effective in terms of blocking the energy flow.
Since coal comprises the majority of energy production, and coal is fairly simple to source, that's one big obstacle for an embargo/blockade. Then there's the question of gas and oil, which again, would be extremely difficult to cut off to reach China's pain point:
Not to mention the domestic sources of energy yet to be tapped by China:
Oil
Gas
Not only are sources of energy well-diversified, but so are distribution channels:
Russia is icing on the cake, not the cake itself. Good for China, but again, this is an opportunistic move, not a strategic move.