The prefix/suffix system allows the creation of a single command, out of two parts (I.E. one prefix and one suffix, both spoken as part of the same single phrase).
It has nothing to do with the conversational style of commands in your example.
If you want to require a "wake word" like "Javis", you could create a command with the "Make VoiceAttack Start Listening" action as the first action, and turn off (suspend) listening.
When speaking that command, the "Feature On Sound" (as configured on the "Audio" tab of the VoiceAttack options window) will play to indicate listening is enabled.
If you want to add a sound after that, you could add a "Play a Sound" action to the command, ideally preceded by a pause the length of the chosen "Feature On Sound", so the two don't overlap.
Alternatively you could set the "Feature On Sound" option to "Silence" to effectively disable that sound, however note that this would affect all other features using said sound, E.G. toggling keyboard shortcuts.
If you add the "Make VoiceAttack Stop Listening" action to the "I need an orbital strike at my position" command, the "Feature Off Sound" would play when that command is executed (you could add it at the bottom, again so it doesn't overlap with other sounds)
Both the "Feature On Sound" and "Feature Off Sound" can be overridden with a custom sound, as mentioned in the "For fun... maybe" section of the documentation.
Again noting that this would affect all features using those sounds.