On your first point you should read the question of nationalities which Lenin wrote shortly before his death. He clearly wanted to take down the tsarist apparatus after all the existential threats to the Soviet Union were gone.

Where did Luxembourg say Lenin was trying to recreate the tsarist empire? She was critical of the Bolsheviks authoritarianism but If anything she was also critical of the Bolsheviks limited allowance for nationalism and would’ve suppressed nationalism further, she was a strict internationalist.

If they did dismantle the state apparatus before the Nazis came what do you think would happen? The Soviet Union was barely able to turn the tide of the war with a united front and 20 years of intense, brutal industrialization. If they had dismantled the state and Russia was just a bunch of rural locally run villages in a loose confederation in 1939 the Nazis would’ve steamrolled over them and genocided the population.