MK's sword doesn't go through the enemy without dealing damage though. He has some swoosh effect on his particles for all his attacks, his SWORD (you know, the yellow thing) never doesn't hit people where it swings.
And no, I don't believe so. I feel stuff like Forward Smash hits where it shouldn't, and so does Up Smash for sure. I think there are some blind spots really close to their bodies that weren't there in other games, but I really haven't noticed them often enough at this stage.
You full hop rising forward air. It tippers their shield on the latest hit. You retreat away on the rise and react to what they do, as you're free to attack shortly after the apex of your jump. This includes just fairing again, nairing, or sometimes yeah, jumping.
Now add dash assault to this mixture. Forward air tipper hits shield or your opponent does an action to avoid that pressure (such as roll away or spot dodge; I'm sure scrubs won't do this forever, but it's very common right now) and then you have that mother ****ing tornado phantasm wrecking whatever action they take other than hard engaging him (otherwise it's a completely advantageous trade for Marth, shield's definitely poke in this game, and Marth's fair/dtilt AND dash assault poke eventually).