Central heat pump questions

Couple questions on a central heat pump. Do the new central heat pumps work at low temps like the inverters do? Second my only experience with one is about 35 years ago and it blew cold air- what temp air do they produce now? Finally, If I understand COP correctly: if I have a heat pump = 9.5 hspf this means that it's efficiency would be 2.78 and I would enter 278 in this calculator?

https://coalpail.com/fuel-comparison...r-home-heating

Thanks

source https://hvac-talk.com/vbb/threads/2242024-Central-heat-pump-questions?goto=newpost