I think for the music, the "stage opening theme" from Mega Man and the "Get Item" themes were used in the Mega Man confirmation (the former a remix, the latter an import from one of the Mega Man games).
Also, from the looks of it, all of the stages (sans Battlefield of course) seem to be directly ported from the games they are from. Skyloft is clearly a texture import from Skyward Sword (although the graphics are obvious more distinguished, seeing as how it went from like 480p to 1080p).
I know I mentioned this to you in the B-Room, but the alleged two NEW Super Mario Bros. or Super Mario 3D Land stages might be one. We know at least the one above the water moves, as confirmed in gameplay.
I think the confirmation of the return of spiking (Mega Man's Hard Man ability is a spike, which has been shown) should be added to the OP, if it isn't there already (I didn't see it, but I obviously could have skipped it).
Also, the gameplay for Smash Wii U we've seen so far looks very similar to the E For All Brawl demo, but slightly faster, more free flowing offense, and less after move lag (much like Melee). Smash 3DS' gameplay looks a bit more closely related to Brawl, but gives off a particular Smash 64 vibe to that game.
And lastly, the character models of veterans in Smash 3DS appear to be slightly downgraded versions of the character models in Brawl.
I wished someone asked about L-Cancel in those interviews.
The land move lag looks very minimal, so something of an automatic L-cancelling mechanic may already exist via just everyone having less landing lag while attacking from the air to ground (which would not just be limited to aerial attacks, but to special attacks and item-based attacks as well).
Didn't that happen in Brawl too. He wasn't revealed until later, even after Peach? I can't remember.
Nope, you're right. Yoshi was the last of the original 8 revealed in Brawl. I checked the Brawl Dojo, and it is 100% true.