Is vasovagal syncope a "disease" or condition?

Neither. It is describing an event, like fainting. It can, but does not have to, occur with cardiac issues, carotid artery issues and dehydration...To name a few reasons.

Related Questions

Can you have vasovagal syncope and seizure disorder?

Yes, together. Different mechanisms and treatments, but not unique to have pts with both. Doctor just needs to sort out.
Yes. You can have both. Work with your neurologist to determine which one is the symptomatic cause.