1. Character needs to be faced to the Y+ axis in the reference pose.
2. In order to use Ik solvers, character limbs hierarchy should consist of 3 (for bipeds) or 4 (for quadrupeds) major bones.
You can attach/parent extra (twist/roll) bones to the major bones but hierarchy order of the major bones should be the same.
3. If your characters limbs are absolutely straight in the reference pose, it is impossible to calculate right location for pole vector controller during creation of rig.
However, in case when limbs are straight, you can use Pole Vector Simple mode to find pole vector location.
4. Controllers orientation is defined by orientation of bones. System supports any bones orientation. However it is more comfortable to work with rig using at least some basic orientation where most of the bones are oriented to the next bone in hierarchy.
5. Automatic eyes rig requires 3 bones for each eye. For reference you can use boy_SKELETON asset from examples project under
eye_left – influences on left eyeball
eyelidLower_left – influences on left lower eyelid
eyelidUpper_left – influences on left upper eyelid
It is better to use world orientation for this bones.
6. Realtime viewport update should be enabled.
7. Allow Translucent Selection should be enabled.
All rig controllers have translucent materials. Translucent material allows to see controllers on the top of the character mesh.