Not common. "non-epileptic seizures" can also be referred to as pseudoseizures, psychogenic, or cryptogenic seizures. They are not due to abnormal electrical activity in the brain, like epileptic seizures are. Pseudoseizures are commonly related to other neurologic or psychiatric problems, including mood disorders. These problems are relatively common in lupus, and could be related to pseudoseizures.
Not really. Epilepsy and seizures are synonyms (mean the same thing). They are a well known complication of lupus but are not really very common.