varies, depending on the species.

No, they have the same anatomy regardless of colour

The anatomy books show what are normally seen, five vertebra... There are many variants in anatomy, and someone with four lumbar vertebras isn't abnormal, just someone who is a little different, but still normal. You might have something we call a "transitional" vertebra, such as an extra thoracic vertebra merged into a lumbar, or maybe a lumbar vertebra fused with a sacral vertebra... Still normal...

Caudal, and cephalic is just the opposite--it means toward the head.

The apophyseal joints are synovial joints in the vertebral column, between the superior or cranial articular process of one vertebra and the inferior or caudal articular process of the vertebra directly above it.

See the link below: