If you're still looking to mod the battery icons they are in framework-res.apk, the systemui ones don't change them, at least on my og transformer they didn't. The wifi icons as well as the notification menu images.
if you can, I think a white battery icon / wifi theme would be awesome. I'd do it myself but I don't have the time with college since my classes have been picking up alot.
One thing I could never figure out is how to change the clock color, I think an xml file in frameworkres controls it but I'm not sure.
TF101 16gb | 1.4ghz | Revolution HD | Early Adopter
TF201 32gb | AG | BB8 4.2.2
Next Device: Tegra 4 Transformer