Not fast enough. The Russians were already saddled with extremely outdated equipment at the start of the invasion.
It was still nothing compared to the efficiency of the modern weapons being provided to Ukraine. Ukraine doesn't need even a quarter as much manpower to mow down the same number of invading Russians.
Oh I believe you, but that just means they'll lose every last fighter in Donbass instead. What do you think that will do to public sentiment against Putin inside of Russia, given that it's already souring? Military recruitment/enlistment offices are being torched left and right as well. Hiding away in a bunker will only keep the scared little mouse safe for so long.