Being able to play with the fabric of time (Ocarina songs), space (as shown in your comic) and matter (with the many masks) in the face of everyone with NOBODY noticing is part of Majora's Mask's fun, don't you think?
Japas is so zen... ^^ I'm not sre what else to say, but I know I wondered about that too. usually a sudden appearance is kinda weird, and Link usually takes it up a notch. 'Cause hey, standing in the middle of a crowd and screaming at the top of your lungs as you change species is usually bound to attract attention...>) Loving Link's expressions the most here. I think Mikau might have really rubbed off on him. XD
Zora Link does look like Mikau to some extent, but Mikau and Link merge their bodies so the end result has more similarities to Link. I would guess that the masks might hold some ability similar to the Stone Mask of sorts, in that they make the viewer accept the merged figure as the one who Link merged with. So the Zora Mask makes the Zoras accept Zora Link as Mikau, despite his differences.