Since you are training to be a social scientist, you should read the chapter "Gilles Deleuze and Félix Guattari" in Alan Sokal and Jean Bricmont's book Fashionable Nonsense: Postmodern Intellectuals' Abuse of Science (published in French in 1997, then in English in 1998). Sokal and Bricmont argued that the use of scientific terms by Deleuze and Guattari and other authors is often nonsensical. "If the texts seem incomprehensible, it is for the excellent reason that they mean precisely nothing."
Sokal and Bricmont included a very lengthy quotation (two pages) from one of the books that you tried to read, Guattari's Chaosmosis: An Ethico-Aesthetic Paradigm, and they commented: "This passage contains the most brilliant mélange of scientific, pseudo-scientific, and philosophical jargon that we have ever encountered; only a genius could have written it." I think Sokal and Bricmont were right: There is no question that Deleuze and Guattari were brilliant users of language, but their use of language often seems to be a kind of avant-garde art, perhaps not too distant in spirit from Dada or Fluxus or Assemblage (the latter is in fact a prominent concept in Deleuze and Guattari's books). Deleuze was explicit about this in a 1973 letter (republished in Deleuze's 1990 book translated under the title Negotiations): "Or there's another way [of reading]: you see the book as a little non-signifying machine, and the only question is 'Does it work, and how does it work?' How does it work for you? If it doesn't work, if nothing comes through, you try another book. This second way of reading's intensive: something comes through or it doesn't. There's nothing to explain, nothing to understand, nothing to interpret. It's like plugging into an electric circuit." Notice Deleuze's word "non-signifying"—which is approximately equivalent to meaningless.
In their epilogue, Sokal and Bricmont tell the story of a student whose experience was similar to yours: "We met in Paris a student who, after having brilliantly finished his undergraduate studies in physics, began reading philosophy and in particular Deleuze. He was trying to tackle Difference and Repetition. Having read the mathematical excerpts examined here (pp. 161–164), he admitted he couldn't see what Deleuze was driving at. Nevertheless, Deleuze's reputation for profundity was so strong that he hesitated to draw the natural conclusion: that if someone like himself, who had studied calculus for several years, was unable to understand these texts, allegedly about calculus, it was probably because they didn't make much sense. It seems to us that this example should have encouraged the student to analyze more critically the rest of Deleuze's writings."
Deleuze and Guattari's use of anthropology was also problematic, as Christopher Miller showed in his 1993 essay "Beyond identity: the postidentitarian predicament in Deleuze and Guattari's A Thousand Plateaus".
It should also be noted that Deleuze was, on occasion, capable of writing entire essays that were completely lucid. His little 1972 essay on Hume is a model of clarity. And some of the essays in his 1993 book Essays Critical and Clinical are quite good. The essay in that book on Alfred Jarry as a precursor of Martin Heidegger shows the connection between Deleuze and Dada that I mentioned earlier.
Incidentally, I found this question through a Google search for "John Dewey" and "Nicholas Rescher" (who both appear in the question)! How delightfully off-topic from my original search.