دوپہر کا کھانا

It is neutral. It's used in both formal and informal settings. For very formal occasions, 'Zohrana' is used.

No, that would just mean 'of the afternoon'. You must include 'khana' to mean lunch.

Usually a meat or vegetable curry (salan) with roti, or Daal Chawal (lentils and rice).

You say 'Dopehar کے کھانے کا وقفہ' (Dopehar ke khane ka waqfa).

It changes to 'ke' when followed by a preposition like 'mein' (in) or 'baad' (after).

Yes, 'لنچ' (Lunch) is widely used and understood in all urban areas.

In traditional homes, yes, on a cloth called a Dastarkhwan.

'Khana' is the general word for food, while 'Roti' specifically means bread but is often used to mean the whole meal.

Not really. Brunch is usually called 'late nashta' or just 'brunch'.

In many traditional families, yes, though in modern working families, dinner is becoming the main meal.