Making dua after Eid Salaah

Q: Is it permissible to make dua after the eid salah before the khutbah, thus delaying the khutbah and not making dua at all in the second khutba? 

Did Nabi Sallallahu Alaihi wa Sallam, the Sahaabah. or any of the four Imams or the fuqaha of their madhabs mention making the dua between the salah and khutbah?

Joining salaahs when travelling

Q: Is it permissible to join the salaahs when a person undertakes a journey and is a musafir? 

Example, you are leaving a country and it is zuhr time so before the flight you join Zuhr and asr? Or you visited a country and you go to a shop and maghrib time sets in so you read maghrib and Isha together? Is this permissible and if not, does one get a sin when they do it?