Salamun alejkum. There is a end if Maghreb time here... The Maghreb twilight is in the west, where the sun sets. When the twilight (persistent) is above 180°, it has past the northern side, meaning it (the sun) is on its way up, meaning the twilight is now in the east, where the sun rises, and that’s when Fajr starts. So there is a end if Maghreb, a start of Fajr, although the persistent twilight. Allah knows best.
This is not the way to decide this issue. Get a group of masjids together. Find a commission a group of scholars to conduct a detailed study for a few weeks or months. Get a professional to write a detailed thesis on the issue. Recommend solutions. Provide detailed proof for solutions. Draft a policy! Execute! Anyone questions, provide study and reasoning for choice! Done!
Only lazy people combine it you can only do it if you on a journey not on a regular basis You can sit on social media till Fajr but you want to pray the two salaah together you are answerable to Allah for your lazy ness
Easy for you to judge. What about young children who go to school? They have to sleep after isha so around 11, wake up for fajr and then try to sleep and wake again. Personally I can only sleep 4 hours a night during summer and it's not easy to function on this amount of sleep so don't be naive and judge people based on your circumstances