I think you might have a hard time arguing that sanctions are illegal or unilateral given that many of them were voted on.
Nope. These were voted in by one party to the war. Rest of the world has actually been busy doing business with Russia. In fact, FT and Economist report that Russian economy grew faster than most European economies.
Russia is in a war economy. GDP = Government Spending + ....
So is NATO.
As an aside, even in peace times, US Federal government employs 12 million people.
The whole goal of sanctions is to induce behaviours change without resorting to actual weapons.