A. Yes, You can.
Lithium Batteries are completely dry batteries with no spilling issues unless physically punctured. You can install the battery in any orientation in your Electric Scooter but keep in mind that the BMS is installed on the top of the battery. So do not completely invert the battery’s orientation (upside down) because doing so might put the pressure of the battery on the BMS. The weight of the battery might damage the BMS.