It's easy to change spectator cameras. Performance might be impacted.

On the top right corner of the game window, click the photo icon :
Then click the bigger icon to show all the cameras !
The drone one is keyboard controlled and can even kill enemies (and might be killed too, I haven't tried)

To open the console, it's the same as the Source engine : Click the key under [escape] : [ ` ]
You have to be in qwerty, azerty won't work (Try alt+tab to swap layout).

To close the window, just it the same key again !
By tapping help, the game shows you some commands

You can try mutators like movespeed, setgravity, timescale or noclip to have fun !

Have fun !