Fallbacks with custom shaders? Fragments?

I was curious if the TSE currently supports setting up fallbacks for custom shaders as well as the in house ones...I would presume so, except it sounds vaguely like something similar to fragments are being used here. Are we looking at an easy drop, set up some scripts, and go situation here or something more strenuous in order to support a fallback path of our own? I was somewhat concerned to see the procedural shaders outside of the pipeline from custom entirely...how hard will it be to hack up this section and customize?
Secondly, I noticed mention that fallback to fixed function pipeline would be implemented, but wasn't yet? Not trying to rush it, but I would like to confirm that this will indeed be the case in the future.
As we move from Early Adopter's through various versions, will we be seeing some good 'changelogs' that allow us to at least get a good gander at what changed files were modified for, an overview at least? I understand there is a certain push to keep developing in the TGE until the TSE is entirely done...but honestly at this stage of the game in our situation I would prefer to take the TSE as is and start flipping through it to find where I'm going to overhaul things. This would be a lot easier to cope with if I could rely on some decent data, or perhaps cooperation with issues, from GG to bring things in line with the new feature sets produced by the staff members.
On a related note, how often is/will the version exposed to us be updated? Is it getting updated as work gets done on it, or in sections at regular/irregular intervals? How big a jump will I be making each time with the source?
And my final question (I swear...) is how applicable are the various resources and add ons from the old Torque? Obviously I'd hope all the 'sound' and 'model' type resources are still valid, but I'm more interested in the code overhauls...things like lighting and the like seem out, but has for instance the AI system overgone an overhaul to work with new terrain systems or the like? i.e. is the rest of the code outside of the rendering pipe fairly familiar looking?
Thanks a bunch.

David