It seems to me, struggling with the myriad of political and sexual orientations of various Surrealist, misses a much bigger picture.
What's interesting to me about Surrealism as a movement was its attempt to introduce a different psychological dimension into just about every medium it touched. The politics of its many different followers seemed a secondary attribute. I think we have to remember that both Fascism and Communism were reactions to the dominance of a bourgois modernity, so too with Surrealism, and hence anybody who dabbled in surrealist ideas could justify themselves on either side of the political spectrum of the period.
Bunuel for example was both a Surrealist and a Commie. In Hollywood it certainly had an effect as the pyschological dimension to many of the cinema noir flicks. You can certainly see its influence on Hitchock and actors like Peter Lorrie who practically adopted a surreal creep as his personnae. In fact, it might be worth tracing out the McCarthy Hollywood hearings as a bougeois political reaction to what was becoming a very disturbing trend in US film making and its evolution of anti-bougeois art making.
I think what's important, which the letter by Freud suggested, was the anti-bourgeois element---that the rational, clean living, and social norm of middle class life was an illusion and a cover-up, that the `truth' was to be found in a different realm. There were a lot of consequences to this general idea that lead Bunuel and others into pretty violant attacks on religion, particularly Catholicism---no doubt for its sexual repression---at least in Bunuel's case. The whole anti-bourgois theme in Bunuel lead to the left and depictions of the crushing effects of poverty and its distortions of psychological dimensions, which you find in Los Olvidados, or The Forgotten Ones.
There are a lot of antecedents to Surrealism, since at its core it's a branch of Romanticism. Edgar Allen Poe and Charles Baudelaire come to mind. In the US in the 1930s, French surrealists had a big influence on painters like Arshile Gorky and Jackson Pollock, and may have had some effect on the NYC jazz scene---Thelonius Monk in particular. Nina Simone recalled the early Monk experiments as `creep show' music. The link can be seen in spontaneous improvization, in strange melodic lines, dissonance, etc. In some sense you can conceive the traditional western harmony as a norm, and then its extensions in 12-tone and other developments as the altered psychological state, a new realm. Following this lead you can trace these from an expressionistic movement into a surrealist movement. You get into a wierd dialectic like that in Mann's Doctor Fautus, and by extension Theodor Adorno. The key here I think is to understand the profound anti-bourgois element in its psychological dimension---and particularly these developments as a tangible threat to the psychological and political quietism of the bourgois order.
In painters, there are many different ways to play with these altered psychological elements. Picasso uses his biomorphic style of the 1930s to evoke something like it in The Girl Before the Mirror among many other paintings. With the Americans the `gestural' painting experiments were combined with some of Picasso's stylist elements in Gorky, Pollock, de Kooning and others. Other directions are found in the work of Juan Miro and Rufino Tamayo. One of the more disturbing examples is Pavel Tchelitchew's, Hide-and-Seek. It's worth spending some time looking at this painting for all the things that are hiddened in the imagery---the more disturbing elements of human anatomy. Google it and view close ups. The pictorial antecedents go way back to Bruegel, Grunewald, and Bosh.
I can't come to any conclusion except that Surrealism is still with us, or me at anyrate. It would be very difficult to trace out its influences since they have been ubiquitous. Maybe the way I look at Surrealism in broad terms has to do with the subterranean mythological currents that underlay Modernity. The world is most definitely not a bright shining room with nice things around, and always polite company to engage.
CG