Regarding #3 premise of Rahulvai: I think it has been well confirmed fact that people of Kapilvastu, and Lumbini at large, 2500 years ago spoke the language hitherto known as "Paali". Regarding #5 premise: It is also a well accepted fact (I hope) that Nepal, as we know it, did not exist in any shape or form 2500 years ago, unless, you are referring to Nepal Khaldo, in which case, the boundaries you mention are the peripheral hills of Kathmandu Valley.