"그는 집에서 걸어가요."
Translation:He walks from the house.
They are not correct, 걸어가다 is a combination word of to walk and to go - "걷다" and "가다", so it literally means "to go by walking." It differs by the verb to walk by specifying there is some start and end destination.
Could thos also mean he walks at the house? If it was using a location like the park how would that be distinguished?
I think that with 걸어가요 (go by walking) we know that he isn't walking around inside the house.
That would be 그는 집에서 걸어요. As previously mentioned in the comment above, the 가 in the 걸어가요 makes the difference. This is what I understand: 걸어요 means walk. 걸어가요 means walk+go, with the 가 indicating that he is leaving somewhere.
Would "he walks from HIS home" instead of THE home be wrong? So many things are implied in korean I'm not sure what is acceptable.