Yes, Hotkeys, Control group and cycling through your units is important for better multitasking. But giving yourself time to think about stuff is also very important, you know this feeling when you are watching pros play and think that it looks slow? That is because you have time to think about stuff.
What I did to get better at multitasking is something i did during my SC2 zerg days: i set a timer to ring once every minute.(for SC2 it was the queen cycle) When I here the ring :
I check my res and the distribution of my vills ( do i have 34000000 wood?, I am making kts do i need 4959 vills on wood )
I look at my global queue (nice no production better change that)
I look at the mini map
I move my scout
I think about my game plan.
At the beginning i only did one or two of the things, this is were hotkeys and control groups become important! they enable you to do more.
What I noticed is that you often look stessed at game but are actually doing nothing, so being fast is not the problem, remembering “to play the game” is the problem 11.
When you get better you can do this cycly more often, and you will *soon* no longer need the ring from the timer. (*soon* meaning thousands of hours of playing and loving and hateing the game.)