Source for RepRap basic requirements (no replies)

I am in the process of adding stepper motors to my small metal working lathe with the idea that, as well as acting as a CNC lathe, it will provide the movement framework for a 3D printer, by adding an extruder.

In spite of a lot of Googling I haven't been able to find any website with information about the basic requirements for 3D printing, which must have been at the root of the original RepRap design. Things such as ...
What is the minimum and maximum speed for movement of the extruder head while it is extruding plastic?
What is the minimum size of features that can be printed, or what governs this limit?
What precision of positioning is required for the different axes?

If anyone has a link to a source for this data I would very much appreciate it.

On a slightly different topic,
I have also been unable to find any website or forum that explains or discusses the principles underlying the RepRap firmware, such as Sprinter. For example what are the essential features for the operation of the stepper motors and what "gotchas" must be avoided. It's almost as though the firmware design appeared on earth fully formed and ready to go.

Again, if anyone has a link to a webpage where this sort of thing is discussed I would appreciate it.

Thanks

...R