OK Ben,
On 1.) the lack of knowledge about what constitutes the dark sector is something several speakers touched on at FFP11. We don't know exactly what dark matter or dark energy is, so cosmologists are taking a lot on faith IMO. And as you note; the scale dependence of dimensionality is important to consider, and suggests a fractal character to spacetime.
On 4.) yes Twistors are very cool. They address some of the issues you mentioned were raised about points by Grothendieck - on Ian's forum page. They replace points with Rays, as the most fundamental level of structure. I imagine that relates to the concept of causal structure quite explicitly.
On 7.) a holistic approach is essential to complete understanding, and it offers insight that is complementary to those obtained through reductionist means. And as for the sum over histories; you need to learn more about Feynman's forgotten gem - Hamiltonian Phase Space Path Integrals.
Basically you are then looking at dynamism straight on, as a Hamiltonian in phase space, rather than working in the kinematic space of the conventional Lagrangian formulation. The cool thing is that this incorporates quantum uncertainty at the outset, but often resolves into a simpler functional integral along the way. I'll look up a paper by Steven Kenneth Kauffmann you should have.
All the Best,
Jonathan
