Depending on what you’re wanting to look at, the single best survey in English (I’m assuming you don’t speak Russian, though if you do, that’ll be an entire other answer lol) is, in my opinion, Thunder in the East by Mawdsley. Glantz and House’s When Titans Clashed is also pretty good but it’s been surpassed by Mawdsley in my view. Bellamy’s Absolute War I’ve heard is decent by some colleagues but I haven’t read it. Alexander Hill also has some really good works on the subject, The Red Army in the Second World War is very long but a very good look at the Red Army specifically and it’s blatantly better than Glantz’s attempt to do the same. I’d also throw in his The War Behind the Eastern Front which is his look at Soviet partisan operations. He makes a few comments regarding German reprisal attacks that have been criticized but it’s otherwise a very good text on the subject.

Now additionally, I feel any actual look at the Eastern Front is incomplete without a regard for the Holocaust which was, after all, an operational goal of the Nazi war in the east and any examination of it without a regard for the Shoah is incomplete. Snyder’s Black Earth and Bloodlands are excellent for this, the former is specifically looking at the Holocaust and the latter looks at it as well as Soviet repression and extermination actions in this period and before. You might also be interested in Smelser and Davies’s The Myth of the Eastern Front which is a historiography examining the construction of the popular myths regarding the Nazi-Soviet War, in particular the minimizing of the Holocaust and the role of the Nazi German military.

Now as for your second set of questions, generally Beevor is kind of someone I tend to avoid, but he is still a reputable historian, if a general one. In my experience he doesn’t so much tread new ground but likes to examine already examined areas and occasionally expand understanding from there. His book on Stalingrad as well as on Berlin are much in keeping with this. He gives a decent if general survey of the Battle of Stalingrad with a decent amount of archival work to back up his assertions even if I disagree with a few of his characterizations of the circumstances surrounding Uranus and what not. It’s about five hundred pages so shouldn’t be too long a read if you want a specific look at Stalingrad.