Kana would be slightly easier to read if we spent as much time reading in Kana as we have in Kanji.
Hangul has some funny rules around patchim that need to be memorized. Kana does a great job avoiding this, so on balance kana is probably just fine compared to Hangul.
I don't think so. Kana just don't have enough entropy compares to Kanji. A kanji can be compose with up to twenty strokes with high variety of stroke patterns. Those excessive complexity make it identifiable even in extreme situations. (Blurry or tainted or whatever situation). In some case, a kanji with half of its size masked still be decoded without any ambiguity. But this will never work with an voice based language.
