True and false; false because the scaling does not affect the damage type- in fact, half of his damage is magic (his E and ultimate) and armor won't stop that. True because yes, he is primarily auto-attack based and Ninja Tabi is good against that.
I SEE WHAT YOU DID THERE.
And I agree, although I imagine it could be based on what he decides to max first. I know Edge and Inuki maxed his W first which made direct fights much easier (or tougher, depending on the perspective) and his sustain is actually kind of high once he's below 50% health since the healing from the, well, healing half of his W is actually tripled in that situation. Personally I tried maxing E first for the extra ranged damage and slow duration, keeping them in auto-attack range longer; that would likely result in more a more pushy thing, but, at the same time your damage isn't limited to being in their face. Admittedly, it did seem kind of underwhelming. I don't know, I don't care much for him anyway.
It wasn't that big of a change...