I think it's tantric when the five Ms are used:
madya (wine)
māṃsa (meat)
matsya (fish)
mudrā (parched grain)
maithuna (sexual intercourse)
No, that would fall under vamachara, of which it's well known for (among other things) although IMO those are not necessary to practice vamachara it's just very common in a lot of traditions and lineages. Substitutes can be used instead too. Tantra doesn't have to be vamachara and usually isn't. Tantra to me in the widest definition is an at least somewhat esoteric or almost magical(more like ritualistic) tradition, with a focus on yantra and mantra work... I guess in a literal sense I see Tantra as mantra+yantra as my understanding is that in someway linguistically it means that. I'm no expert though, I could be wrong on the etymology.
But on a certain level when you really come down to it, there isn't much difference between the many kinds of practices
when you strip them to their functional core. There are only so many ways you can worship, meditate and chant ect even if the tools you use vary wildly... it seems a lot of definitions come down to historic usage and culture and so is one huge gradient with overlapping terms, different spins on meaning and different connotations, not some kind of top-down categorization where things fit in discretely.
EDIT: some small clarifications