Hi
There are no hard and fast standards here but these are just a few general guidelines :
I have seen in various places (magazines, on screen …) that some set ups have a multi-boned spine - is this IK or FK?
A multi-bone spine usualy implies “Follow Curve IK” or an IK chain thats controlled by a curve
Common on more realistic or rather Hi-Res characters that require fine control of the spine(Smoother deformation of the body too)
I've used Multi-Chain spines to, for example make a Winged character fly and smoothly transition to a walk. In this case the Root of the heirarchy had to move from near the wings(flying) to the Pelvis(walking)
How can you get eye lids to follow an eyeball's surface and not intersect?
you could try “soft” grouping the points you want to animate and Rotate them around the centre of the eyeball , ie place the transforms pivot at the eyeball's center- for instance
I also have a lot of trouble with colapsing elbows and knees - characters, not mine - especially at extreme bending of joints - any suggestions?
Insert another small(er) bone where the real joint would be
for example instead of ——-*——– try ——-*–*——-
check out the video called “Realistc Arm Setup” for a neat example. You may even layer Blend deformations that are driven by boneangles on top of your capture to tweak those pesky joints
Are there any general rules to getting a good character set up?
One I swear by: Test Test and Test again before laying down a single keyframe
Coming from a Maya background this rule was the Holy Grail. Houdini offers much more flexibility in that you can tweak the rig almost anytime you want.
What's most important to remember is that a rig needs to be clear and simple to animate with.
so when it comes to animating - Keep It Simple
You may want to go through rigging tutorials from other softwares too, since the principles are the same. Highend3d or 3dbuzz are good places to start
Hope this helps
cheers
tallkien