Hi Lui,
If you maintain Other charges (ZOCH) as statistical, value will not be added to the net value.
It is better you maintain two different condition types to capture Other charges.
Please maintain the first condition type before tax condition type, but not as a statistical.
Second condition type also can be maintained before tax condition type, but as a statistical.
As for as MWST is concerned, you can maintain the tax percentage using tax code. But it is also necessary to maintain in VK11.
Regards,
Raja Durai