Delta design considerations/theory

Hi everyone,

I'm looking into designing my own small delta Reprap from scratch, mainly for the fun of designing machines. However, I'm a bit at a loss when it comes to details on delta Reprap theory; I can not find anything useful in the Reprap Wiki (I know it's probably hidden somewhere, but where?). I'm interested in knowing some fundamental design principles and challenges and how people solved them in order to learn from them and adapt them for my own design.
Some examples of what I'm interested in include (but the list is not exhaustive):
- How do I calculate the optimal arm length?
- What bearing options do people use for the arms and what are their tradeoffs? (I've seen ball bearings and magnets, but I haven't seen any discussion on WHY some of these designs offer desirable properties and what they are)
- How important is the mass of the print head?
- How accurate should positioning of the three axes be?

Unfortunately, the Reprap Wiki does not seem to be very conclusive (or very well-structured) when it comes to these questions. Where can or should I look for answers? Given that everyone and their dog builds a delta Reprap these days, they surely must exist.

Felix