You can only use a single forceast, I have used a time mid-point with satisfactory results regarding flight fuel burn using the enhanced grid function.
METAR & TAF look to be ok but as you mention WAFC and Tracks are outdated. Tracks could be switched to manual mode and pasted in if required.
I'll follow up with the dev at the end of week.
The Prepar3D folder should be just that, the root of P3D
Documents folder again should be the root of Documents
Then just tick the addons unless you require a custom configuration.
I wouldn't say the majority of Europe uses dme's calibrated to zero at thresholds, certainly a few do.
The antenna may be located with LOC/GP or elsewhere. EGLL for example has the antenna placed mid-point of the runway serving both ends calibrated to read zero at the thresholds. Trickery.