My definition would be mania (intensities vary), your "max" in symptomatology, but a severity which makes it (just) possible to suppress it enough to function, provided (momentary) suppression doesn't lead to escalation into mania. So, basically, you know you are at your max and suppressing it doesn't cause you anxiety (so severity is mild).

I'd say for those with mania, a better word for it would pre-mania, as it is sometimes less stable and so qualitatively (sometimes more than at other times) different.

Basically, if you can stay relaxed, you're fine. No break on your behaviour at all or no strange, concerned, surprised looks sounds like normal behaviour to me.

"Actual" definition is symptoms of mania but without causing severe, functional impairment.

The word hypomania is badly chosen: could be anything (except mania).