The class of travel should make no difference- it is no more acceptable for parents to let a child run havoc at the back than at the front, nor is it acceptable for other pax to complain more about children at the front than at the back.

In terms of bassinet - forget it. Unless very small, most kids don’t fit in the cot after 4-6 months and in the Z seat after 10-12 months. Best to let her sleep at one end of your seat or next to you, or let her sleep in your seat while the 2 adults dine together.
I’d also advocate to feed her what she wants when she wants. All of this worked wonders for me