Were scared and seemingly-untrained soldiers sent directly to the front, experiencing battle within a very short time of arrival?
Were the new Soviet soldiers simply corralled like scared cattle and sent into battle or was there a sense of order and patriotism from the recruits?
Were they often attacked as they crossed the Volga?
Were there often desertions when the Soviet soldiers saw what they were up against?
Were soldiers experiencing daily combat or was there a sort of rotation period to safe areas?
Were there any safe areas?
And how did Germans feel about mowing down waves upon waves of Soviet soldiers?
Enemy at the Gates is not exactly know for its fidelity to the truth, even avoiding the fact that Zaitsev's memoir which it borrows from is kind of full of shit itself (There is no record of the sniper duel with Konig for instance).
Here is a piece I wrote earlier which addresses the use of human wave tactics as portrayed in the film:
There are three principle ways that human waves were utilized during the war.
In the very early months, the fight was exceptionally desperate and the Red Army often found themselves with no alternative, as they lacked heavy support, and in some cases even enough rifles. Massed charges happened, and there are even accounts of Soviet soldiers charging with their arms linked in solidarity (or to ensure no one chickens out if you are cynical) as they lacked rifles. Wasting trained soldiers on this makes little long term sense though, and it wasn't utilized in latter phases of the war.
The second, and more common use at least through Stalingrad, were the citizen levies (Narodnoe Opolcheniye). There weren't soldiers, but civilians pressed into service and thrown against the Germans to buy time. Some were armed, some weren't. In some cases they were forced at gun point. Most members of the Opolcheniye had no training, and survival rates were low, to say the least. those that did you be absorbed into the Red Army eventually. To quote from an instance outside Leningrad:
"Altogether over 135,000 Leningraders, factory workers as well as professors, had volunteered, or been forced to volunteer. They had no training, no medical assistance, no uniforms, no transport and no supply system. More than half lacked rifles, and yet they were still ordered into counter-attacks against panzer divisions. Most fled in terror of the tanks, against which they had no defence at all. This massive loss of life–perhaps some 70,000–was tragically futile, and it is far from certain that their sacrifice even delayed the Germans at all on the line of the River Luga."
The scene in Enemy at the Gates is possibly inspired by the workers from the Barrikady Ordnance Factory, the Red October Steel Works and the Dzerzhinsky Tractor Factory, who were press-ganged and charged at the German troops on August 25th, 1942.
- The final type we see is with the shtrafniki - soldiers put into punishment battalions. They were soldiers who had committed crimes, or political prisoners of the gulags, or kulaks, and other undesirable elements, who were atoning for their crimes (real or imagined) with service in the worst position in the army - in many cases the alternative was a death sentence anyways. Service would be for about three months, and if you survived, you would return to a normal unit. But survival wasn't easy. These units would be used for such wonderful roles as human mine-clearers, or in the parlance of your era - "Forlorn hopes". Some units would have 100 percent mortality rates, although the overall survival rate wasn't quite that high! Close to 500,000 soldiers would service in the Shtrafbat by war's end.
So thats about the sum of it. The use of proper troops as seen in the film probably wouldn't have been happening by late 1942, and I haven't read anything about Stalingrad to imply that they were.