I got my visa approval for FY2017. I have all my documents with me. My wife is currently studying on f1 visa and we have applied for her H4 (i-539) in mid-august. My question is can we take our date together without her approval using my dates?
Yes, you both can appear for stamping together - you for H-1 and her for H-4.
I have another question if you can help. My wife is already studying on f1 and we have applied for h4. Can she return on H4(after approval) even though she is studying? Wont she be converted to F1 then?
She can enter US on H-4 and that would become her visa status. She can continue studying on H-4, or stop studying - her wish. If she continues studies on H-4 then let DSO know about it.