We refused from the use of small fasteners and used PCB nuts that are immediately soldered to the board. This simplifies installation and allows you to spend less time on assembly, especially in large-scale production.
We made pads on the FC board to connect the buzzer and included it in the kit. It is up to you to decide to connect it or not.
There is no need to connect and search for a mounting location for a separate USB board - it is simply located on the front of the FC board.
Powerful BEC units are based on quality components. Selectable voltage for VTX/CAM and SERVO units.
It doesn't matter on which side the battery is located - it will be convenient in any case.
If you are using a single motor, the signal contacts (S1, GND) can be connected directly to the PDB board, at the same time as the motor is powered.