I will work on the next two points that QuakerK makes on Quaker Glimmerings, because they go together:
3. Early Quakers didn't stress the physical resurrection. Again they got a lot of flack for this. I've seen this in the Nayler writings that I have read--they stress the idea of "spiritual body."
4. They discounted the overriding importance of Christ's death on the cross: not that it was unimportant, but that by itself it meant nothing, and wasn't effectual without the Inner Light.
I don't pretend to be incredibly knowledgable about early Quaker writings on these topics--maybe that shows that there aren't many! Or maybe I'm just ignorant of them. At any rate, I'll do my best here.
First, I would echo a comment from Wess on QuakerK's post: Friends contemporary with Nayler came to see him as heretical, in that they felt he was going a different way from the goals of the Friends movement. I haven't read much Nayler, so I'm not sure if what QuakerK is referring to is from his earlier or later writings, but either way I'm not sure I would take him as representative of early Friends, although some of his writing is probably still useful and good.
I think in a way it is true that early Friends didn't stress the physical resurrection, but that is at least in part because it wasn't really questioned yet. The Enlightenment was going on at the same time, but I think most people hadn't gotten to the point of truly questioning faith and miracles yet. There wasn't much of a need to "stress" Jesus' physical resurrection because it was assumed that most people would already believe in that. We have to remember that it was a completely different culture and mindframe! Europe was nearly all nominally Christian (with some Jews and Muslims and others thrown in there). Most all regular citizens would belong to some church, probably the state church. Most people weren't converting to Quakerism from atheism, but from other Christian denominations.
Quakers tended to emphasize that followers of Christ will suffer, be persecuted, and possibly die for their beliefs and actions. I think QuakerK is right that early Friends didn't emphasize the crucifixion as an end in itself, but saw it more as an analogy for the lives of the followers of Christ: if people will persecute and kill God, how much more likely is it that we normal people will be persecuted for our beliefs? They focused more on the life of Jesus, following his example and in that way "carrying thier cross."
In the modern era several atonement theories have been put forth to explain the reason Jesus had to die on the cross. The early Friends were working with just one atonement theory, pretty much the only one there was (as far as I know): that of substitutionary atonement, that God had to die as a perfect sacrifice, mimicking the Jewish substitutionary system with the perfect human sacrifice, who alone could cancel out our sins through death. This theory emphasizes the death part of the life-crucifixion-resurrection, and while it has some good parts and some biblical basis, more modern atonement theories come at it from a different direction.
Perhaps the early Friends were unconsciously reacting to this fairly negative way of looking at the life of Jesus, not to mention humanity. As I said in my post yesterday, Quakers tend to be on the whole a more optimistic group in terms of human nature than most other Protestants. Quakers and Anabaptists tended to see the life of Jesus as an example to live (and die) by, and the resurrection as the promise of new and full life in God whether one survives or dies as one follow God's guidance. Although they didn't come up with a new atonement theory I think in many ways they lived it out.
I would also say that perhaps early Friends didn't spend too much time debating the little doctrinal pieces because they felt there were more important things to do--like work against injustice and help others. But I think all these impulses came out of their understanding of the true life, death and resurrection of Jesus Christ which gave their lives and their actions meaning and hope.