vinasp wrote:1. What is the background to these questions, and how should they be understood?
A note from Thanisarro Bhikkhu on SN12.48
The cosmologist (lokayata) schools of thought reasoned from what they saw as the basic principles of the physical cosmos in formulating their teachings on how life should be lived. In modern times, they would correspond to those who base their philosophies on principles drawn from the physical sciences, such as evolutionary biology or quantum physics. Although the cosmologists of India in the Buddha's time differed on first principles, they tended to be more unanimous in using their first principles — whatever they were — to argue for hedonism as the best approach to life.
vinasp wrote:2. What is meant by "all"?
"Simply the eye & forms, ear & sounds, nose & aromas, tongue & flavors, body & tactile sensations, intellect & ideas. This, monks, is called the All." - SN35.23 Sabba Sutta - The All
vinasp wrote:3. What is meant by:"without veering towards either of these extremes"?
Because of the Buddhas right view the Buddha avoids these two extremes. Also answering your Q4 but for now see SN12.15 Kaccayanagotta Sutta: To Kaccayana Gotta (on Right View)
"By & large, Kaccayana, this world is supported by (takes as its object) a polarity, that of existence & non-existence. But when one sees the origination of the world as it actually is with right discernment, 'non-existence' with reference to the world does not occur to one. When one sees the cessation of the world as it actually is with right discernment, 'existence' with reference to the world does not occur to one.
"By & large, Kaccayana, this world is in bondage to attachments, clingings (sustenances), & biases. But one such as this does not get involved with or cling to these attachments, clingings, fixations of awareness, biases, or obsessions; nor is he resolved on 'my self.' He has no uncertainty or doubt that just stress, when arising, is arising; stress, when passing away, is passing away. In this, his knowledge is independent of others. It's to this extent, Kaccayana, that there is right view.
vinasp wrote:4. In what way does Dependent Origination represent an answer to the questions posed?
SN12.15 as above
"'Everything exists': That is one extreme. 'Everything doesn't exist': That is a second extreme. Avoiding these two extremes, the Tathagata teaches the Dhamma via the middle: From ignorance as a requisite condition come fabrications. etc.
Dependent Origination does not give a straight answer to the questioned posed, because the questiones are inappropriate. Dependent Origination provides the means to reveal the misunderstandings from which those inappropriate questions arose. Avoiding the extremes of existence and non-existence (via the middle)
best wishes, acinteyyo