How much gb do you consume playing fortnite and general online games?
Depending on how big a game is, you also use the number of GB. In most cases there will be a minimum requirement specification, which also includes the amount of hard disk space used.
He doesn't mean on the hard drive but in the traffic.
There are lists of which games use how much.
Not much in general. At least if you don't use voice chat.
It will not be possible to generalize that either.
Don't guess a lot. But in general, that's not really important. What is important when playing online is the ping. As far as I know ^^