Wotcher.
"Hi" as the opening for business emails is completely standard and what I'd expect from a colleague. "Dear" for externals. No introduction, just the name, for formal instructions / wiggings from senior people, or the most formal reports upwards.
My internal Dear Sir/Yours Faithfully equivalent would be "Hi Facilities team", etc, for corporate joint inboxes. I don't know what others do, but this one is tricky.
The academics I know tend to sign off with "Best", tout court, which is efficient if silly. "Kind regards" annoy me quite irrationally. If the email is asking for something, you get many thanks (never in advance! ugh!). Otherwise best regards or regards sound businesslike. Or, internally, nothing at all. Best wishes are only for special cases, generally if I hope you will go away now, go right away, and never trouble my inbox again.
I have the honour to remain, dear Sirs and Mesdames, your obd't servant to command,
HTFB