Regarding holding flights....
TL: DR...Yes, they will hold planes for the last flight of the day.
Keep in mind, this was over 40 years ago. So things probably changed.
I was in college in Milwaukee...about 1980. I was flying down to Savannah-Hilton Head to meet my family for Easter. Fly down Thursday, and fly back on Monday.
Due to classes, I had to take a late flight. Even then, it was a 2 PM flight to from Milwaukee to Chicago with an hour layover in O'Hare followed by a 4 PM flight to Atlanta (arriving at 6:30 ET ) and continuing on to Savannah (arriving at 9:30 ET). No plane change in Atlanta, just a continuation.
There was a driving rain storm all up and down the East which extended all the way to Wisconsin/Illinois. Our plane was nearly an hour late taking off. So we didn't get to Chicago until nearly 4. Fortunately, the two gates were literally next door. So I made my flight to Atlanta/Savannah. Fairly easily, because the plane didn't take off until about 4:30.
However, I still didn't have enough time to eat. So I was hungry when we took off for Atlanta. Very limited food service on the flight. At least I had time to get off the plane in Atlanta and hit up McDonald's or something.
Wrong.
Plane arrived in Atlanta about 7:30, ET, about the time it was supposed to take off to Savannah. I was famished. But they wouldn't let us off the plane to get food.
And here's the clincher. Since it was the last flight of the day, they waited around a several hours to allow those on connecting flights to make their flights to Savannah/Hilton Head. Their rationale...They held the flight in Chicago for us, so they should hold the flight for those flying into Atlanta.
Still, no food.
We didn't take off until nearly 11 PM. And by the time we got to Savannah, it was after midnight. On Friday.
Good Friday. A day of fasting.
I couldn't convince my parents that it was still Thursday in Milwaukee. I had to go with no food until breakfast later that morning, and limited food that day.
So yes, they will hold the plane for the last flight of the day.