Re: Punjabi
I thought the difference between eloquence and common language was the rarity of the words used. 
Just take the example of urdu poetry. It’s an awesome piece of work if you use obscure, uncommon urdu words, most of which are mostly either persian or arabic in nature. Similarly, Punjabi is really full of eloquent words. It’s just that the common person won’t probably use such words in their every day language. It’s that, or the fact that it’s old Punjabi. You can’t claim that Punjabi isn’t eloquent. I’m sure the urdu that i speak isn’t eloquent if you have a definition of eloquence.
Gamma: for us kids, urdu has become a language in which the adults speak to the kids. Don’t ask why. That’s what the second generation and I grew up with. So no, to me Urdu doesn’t equate formal setting.
I think the reason urdu is seen as a formal language is because it’s the universal language for the country. In a situation where there a bunch of people from different areas of the country, and each of them speaks a different dialect, Urdu is a language in which they can communicate with each other without confusion.