पास is used when talking about non human things.
नेहा के पास कार है - Neha has a car.
नेहा के पास दो बिल्लियाँ हैं - Neha has two cats.
Neha has two daughters = नेहा की दो बेटियाँ हैं।
You're right partially. नेहा के दो बेटे would translated to Neha's two sons but it would just be a phrase. As soon as you add है, it becomes Neha has two sons.
the oblique case is similar to the objective case in English. In English when we use a preposition we use the objective case. IE To Whom rather than to who, to me rather than to I etc. In Hindi when there is a postposition used the oblique case is used. I believe it has some other uses as well that make it differ a bit from the English objective case, but I hope that helps give you a basic idea.