Are there hotkeys to change the Replayspeed of a replay from x1.0 immediatly to 0 or x0.3 ? I know you can scroll through the speed with , and . but a key which pauses immediatly?
Pauses immediately is P. You can't set it to 0,3 at once though.
You can also use shift+p to enter the next frame if you're paused.
Using E will make you able to edit the replay from the point you pressed E.
[Ctrl + >] and [ctrl + <] will immediately switch you between 1 and -1, so by using this you'll be able to make your replay play inverted with the same speed.