Can periapical xrays show location of the lingual nerve in relation to the lower wisdom teeth? are they ever used in planning wisdom tooth extraction?

Sometimes: A panoramic full face Xray would be preferable with a full cadcam evaluation as the penultimate diagnostic aid

Lingual nerves: cannot be seen on a regular X-ray. They can be seen on CAT scan or MRI. But you can see the wisdom tooth position in relation to the mandibular canal assessing the risk of injury of the inferior alveolar nerve.

No and no: The lingual nerve runs in the soft tissue and would not show up on a periapical or a panorex. A panorex is usually used to visualize the jaw, sinuses, and wisdom teeth, and their relationship to the inferior alveolar nerve.