Can I command an atronach?
As far as I can tell, an atronach waits until it sees an enemy and then decides on its own way to attack. Is there a way for me to control it in any way -- moving it to a different spot, having it attack a specific target, etc?
Solution 1:
Nope, the only control you have is you can choose where it is summoned to when you cast the spell (by pointing at the location).
After that point, it will do it's own thing for 60 seconds without your involvement. It will follow you around until it sees something hostile, and then it will attack whatever target it chooses to until the spell ends, it dies, or there is nothing more to attack.
Solution 2:
No. They don't act like followers and there is no way to command them like you can followers.