I'm not a programmer, help me parse the forcing xml files.

XML was chosen as it is relatively easy to parse files and is universal. There are numerous utilities that can read xml files on various platforms.  Available to most students and researchers is Microsoft Excel.  Open office 2011 Excel, click on the Data tab, click on Import data from other sources and select your forcing file.

Import Xml File

Import Xml File

The tiff raster datasets or images appear black or grey, are they corrupt?

No, the tiffs are georeferenced tiff files ( http://en.wikipedia.org/wiki/GeoTIFF ) used by majority of Geographic Information Systems (GIS). Depending on what tool your using, the data bitness ( http://en.wikipedia.org/wiki/Bit ) maybe completely one color such as black or grey as the data is not visualized correctly. For example the elevation data is 64 bit and the color ramp is from white to black., Your tiff viewer is only displaying black as the 32 bit viewer is "clamping" all the data to black.

But my GIS tool is doing the same thing!

This often happens as the GeoTiff statistics is not read correctly or corrupted. I suggest recreating the statistics using your GIS tool to visualize the data to your likening.