In the preface to the 1882 Russian edition of the Manifesto, Marx and Engels say that the Russian commune could “pass directly to the higher form of Communist common ownership” only if the Russian Revolution (which he saw as inevitable, though it was not inevitable that it would "take[] place in time" (first draft of letter to Zasulich), and in the Letter to Otecestvenniye Zapisky he says that if Russia continues on its path, it will have lost this chance to skip the phase of capitalist development) is supported by wider revolution in the West. Otherwise, the Russian commune “must [] first pass through the same process of dissolution such as constitutes the historical evolution of the West.”
There’s zero approval by Marx here for the notion of skipping the phase of private production/property in one country without a wider revolution.
Marx told Zasulich at the time that education was one of the most crucial factors in the possibility of bypassing the agonizing stage of capitalism.
No he didn’t.
I think it’s really strange to read the main transitional aspect of TGI as Marx “working through his Hegelianism”/this being the main separation between it and Capital, when Marx never had any Hegelianism to work through, and only describes himself as a “disciple of Hegel” (/calls Hegel “my master”) in maturity; wrt alienation, Marx already basically lays out his mature conception of alienation in TGI as a feeling that drives the proletariat to revolution and as a necessary historical phase to create the productive forces necessary for communism (all this as opposed to alienation being a humanist value postulate, as in The Holy Family), and the further detail/development of the concept of alienation (in how it historically arises and manifests itself) in Capital has nothing to do with Marx having further thrown off his Hegelianism, it’s just a direct product of his further economic research where he stops being reliant on Smith (for TGI) and constructs his own political economy.