I know this will not be possible in real time with the voice but we could use a substitute tone (basic synth lead, piano etc) to let us hear it in real time while the software computes the result behind the scenes.
Retime a phrase by playing over it with a midi instrument. The new phrase inherits the words from the old phrase and puts them in with the new timings.
Pitch wheel input to change vocal pitch of existing phrase. Reason does this with its record automation feature. Again, use the substitute tone over the vocals to indicate what pitch synth V is receiving from the wheel.
Vibrato change via keyboard mod wheel. Same as with pitch change, substitute tone plays with the vibrato you will impart onto the vocal take.