Head and arms are worked separately.
The arms are attached to the torso/neck, then the head sewn to the neck/torso.
Not in the pattern as it is optional: Arms can be crochet to the neck/torso during the last round for the body.

Depending on your yarn and hook, and of course how tight or loosely you crochet the size of the figure can vary and so can the yarn usage.

Example:
Using worsted weight yarn and hook size D (3.25mm) the size of the figure will be approx. 10.5” to the top of the head, not including the ears. And the yarn usage was about 161 yard as this was crochet loosely.