Both are fine, but if you are talking to their bodies say hi
everybody but if you want to speak to them and call everyone
there one thing, say hi everyone.
I know, English teacher is a headcase!
HI! Well yesterday I did my grammar class so I should know!
"Everyone is coming" is the correct answer! you would not
say, "Everyone I invited are coming" say it over in your
head, it doesn't sound right!