Over-length does not affect the lost slots. Only the over-height and over-width affect the lost slot calculation for platforms. Cargo with higher weight might cause more lost slots because the platfrom must be loaded in a lower tier on deck than a light weight cargo.
The width of an ISO container is 244cm. Cargo with a width of 245cm has already 1cm over width....0,5cm each side.
No, not in a wooden floor container. The spreaded load per running meter is too high (15.000kg/2,00m = 7.500kg/m). In a 20’GP/OT/HT with wooden floor you can load 4,8t, in a 40’GP/OT/HT you can load 3,0t per running meter. Using a steel floor container extent the possible load per running meter to 7600kg in a 20’ and 6000kg in a 40’ container.