SWIFT is just a messaging system, they can probably still use Telex which is the precursor to SWIFT.
I believe it is. Nobody is threatening sanctioning Russia's energy sector à la Iran.
There are numerous workarounds. Most involve Russia submitting to China. Given how unpredictable Putin’s become, that’s preferable to them being a regional power.
This is almost expected. The calculation being that Russia is safer as a Chinese vassal than a regional power. Settling via CIPS is also more burdensome and thus expensive than settling via SWIFT.