Regarding Q1, I am only aware of 2 major contemporary re-interpretations of DA within the Theravāda. The first, of which you seem to already be aware, could be characterized as simply a more “intimate” extension of the traditional metaphysical/sequential/causal interpretation of DA, wherein the links of DA are said to unfold not just across lifetimes as was traditional, but to also occur in very rapid succession on very small time-scales, possibly even within the span of a single mind-moment (insofar as such a thing as a mind-moment is even a coherent concept, which it is not). Ajahn Geoff gives perhaps the most sophisticated elaboration of this modern interpretation in his book The Shape of Suffering, describing DA is a non-linear complex system whose behavior has fractal/scale-invariant properties. Describing DA as scale-invariant allows the links to apply both at micro and macro time-scales, bringing DA “closer to home” without denying the traditional interpretation. Of course, one could omit such scale-invariant language and take this genus of an interpretation in the direction of outright rejecting the traditional interpretation as Ajahn Buddhadasa seems to have done. There are also quotes of Ajahn Chah—(“The mind passes through the chain of the Paticcasamuppada so rapidly that we can’t keep up. It’s like falling from a tree. Before we can realize what’s happening - thud! - we’ve already hit the ground.”)—that seem to indicate that he was sympathetic to a more immediate interpretation of DA as well. So those are three big names: Ajahn Geoff, Ajahn Buddhadasa, and Ajahn Chah, and I am sure there are many others besides, both before and contemporary with these teachers. I imagine it would be very difficult to find a first example of this kind interpretation because it is so intuitive. And to the extent that the overwhelming majority of “heretical” DA interpretations deviate from tradition, they very likely do so by leaning on the micro side of things as Buddhadasa did and simply denying the extension of their notion of DA as a causal chain into past and future lives.
The second strand of contemporary interpretations of which I am aware is the structural, ontological, trans-temporal, non-sequential, non-causal, non-metaphysical interpretation developed by Ven. Ñanavīra and described in his Notes on Dhamma, published in 1963. I can say with confidence that this interpretation is unprecedented, unique, and is a wholesale rejection of the traditional interpretation rather than a contemporary—(though you did provide what could be considered a much more ancient example in your OP)—adaptation like the previous. The fact that Sartre and Heidegger laid the theoretical foundation for such an interpretation in the 30s and 40s—only two decades prior—is what gives me such confidence that Ven. Ñanavīra’s interpretation is unprecedented and without any historical Buddhist antecedent.
To briefly describe the difference between Ven. Ñanavīra’s interpretation and all the others, Ven. Ñanavīra and his disciples hold that the links of DA are not events that unfold in an even partially sequential manner but are simultaneously-contextually-present existentio-phenomenological realities that permeate and structure any and every possible experience: past, present, and future. In this interpretation, thoughts regarding the metaphysical reality and objective historical timeline occurence of a person’s birth in the past are simply one of many experiential sub-images that, among countless others, together form the more fundamental ontological image of Birth as a necessary existential context that permeates every possible conscious experience whatsoever. To use Sartre’s words, a person’s birth is always present, as past.
Ven. Ñanavīra’s interpretation encompasses and surmounts the traditional metaphysical interpretation. The entire domain of causality and speculative—(always and forever completely speculative! qua Hume)—inductive metaphysics, so attractive to the scholastic, is rendered by Ven. Ñanavīra to be, on the most fundamental spiritual level, simply besides the point.