Shouldn't this be just 저는 공부합니다 ?
It's the same
Is there a reason that 공부합니다 becomes 공부를 합니다?
No, the same. Maybe a very slight emphasis on the noun in the latter case.
Why isn't "I am studying" accepted?
저는 공부를 합니다 literally means "I do [my] studies"
To say I am studying(at the moment) you'd say 저는 공부하고 있어요.
Or 있습니다 :)
Because "I study" isn't necessarily present. It just means that you are a person that studies, while "I am studying" means you are literally in the process of studying.
Could it be: "I do study" because it is saying the verb to be/is?
I had the same impression " I do the study"
Yes I agree. Similarly, 저는 노래를 합니다 means something like "I do a song."
I think that is quite literal, though I don't think it would be wrong (anyone correct me if I'm wrong)
What's the difference between 합 니 다 and 집 니 다?