When to use मकान and घर? Is it like house and home?
Yep. घर is more like 'home', while मकान is more the building itself (house).
Thanks for asking. I had the same question. Very helpful.
When is it यह and when is it ' डस?
I believe the second one is in the oblique case, used when there are some postposition.
When is इस used and when यह? It's not evident from the exercises.