I'm definitely interested in learning C++ before diving into Wii U specifics. The Harvard course you linked looks impressive, but I understand it might be challenging for a beginner. I'll definitely check it out though, and appreciate the heads-up about the learning curve.
Although you mention to be using 7.0.5, the latest compatible with A9LH, you could try flashing an earlier version (such as 6.6.2) and upgrade from there following the official guide. There is useful information here.