A one connection flight will take approximately 10 hours, not including layover times.
Around 4 Hours
The distance between Moscow Russia and Omsk Russia in miles is 1395 miles. So, it will take 2 and 1/2 hours by aircraft.
13 and 1/2 hours
27 hours and 42 minutes.
11 hours 56 minutes
The flight time is 2 hours, 41 minutes.
10 hours
40 days and 40 nights in the Wright brothers' plane
In order to get a meaningful answer, you need to say where in Russia. Seoul-Vladivostok is a very short distance by comparson with, say, Seoul-Moscow or St.Peterburg.
At least 8 hours.
It took me 3 hours to fly from Germany to Russia, so it is probably about the same.