Kindermann's book (in English) is the one big hole in my collection of Leningrad books. I already had the slightly shorter German edition (2002), so I didn't bother. But later I heard there were some really important updates between the editions... The instructive material at the start is great through (maybe even that was improved?)
The Beim book has some brief instructive material, basically two games showing typical ways for White and Black to win. But more importantly he has 35 exercises at the end, which of course I have never bothered to solve
. From a brief look and reading of the instructions, most feature tactical or attacking ideas, for both sides - could be useful to go through after digesting Kindermann's material.
Be forewarned about the actual theory though: I noticed an older thread here where Beim was criticized for sloppy analysis, though he does cover some interesting, offbeat lines that are rarely discussed, like 7...c6 but NOT aiming for a quick ...e5.
The fairly new Marin DVD is supposed to be all about themes and understanding as well. But I haven't seen it, so I don't have an opinion.
For theory, apart from Flear's consistently good work here, the last word is the Malaniuk/Marusenko book from 2014. Though I still go back to McDonald's Play the Dutch a lot - I have the (maybe superficial) impression that he was looking more for unbalanced play, while M'n'M are more concerned with safety and equalizing - to the limited extent those terms even apply to the Leningrad!