Alright, several more observations!
-Selectable characters for high score initials are correct as-is: A-Z, 0-9, along with . and (space).
-"Recreated_Sound18.mp3", aka "dont_know_what_this_sound_is.mp3" is the sound that plays when Felix loses a life (hit by a brick or bird/runs into bricks). It also plays alongside the death sound when the final life is lost.
-Super Felix lasts for about half a second after the "beep" noises end. As for the sound itself, it's less of a "beep" and more of a "blip". The best way I can describe it is a higher pitched note from the "fifjr_second_floor" that mistersinistar made.
-Being Super Felix does
NOT seem to increase the speed of fixing, just moving from window to window.
-Flower pots are placed randomly. After playing a few more rounds there did not seem to be a definite pattern to their arrangement.
-When Felix moves up to a level that is below a flower pot, Felix's head will hit that overhead pot and trigger the sound. This is interesting because if you move up to a level below a pile of bricks, Felix doesn't hit those.
-Birds from higher floors (level 3 and beyond) begin to scroll across the screen right after the current floor is finished and the transition to the next starts.
-I tried fiddling with the Jump button, and Felix can jump during MOST of the transition between the two windows. Even on the actual machines it can be tricky to execute, so I'd dare to say it's fairly accurate as-is.
-Lives
DO continue to add (though not visibly) after the sixth head is displayed. Not sure if there's a limit, but I reached at least 9 at one point. The heads are indeed right-justified, appearing more inward as they are earned.
I also did some playing around with Two Player mode to see if there was anything different in terms of gameplay. First off, the introduction plays for both players (somewhat annoying and lengthy). Players swap out only when the previous player has died, and of course progress made on a level is saved for when the player resumes next. Only visible difference during gameplay is the swapping between 1UP/2UP in the top left corner. I recorded a playthrough, meh as the lighting may be. (YouTube is processing the rotation so it may still be sideways)
During the "PLAYER X READY" screen, a new(?) sound effect plays. Here is a recording from the speaker (I have also placed a copy in the Dropbox):
https://dl.dropbox.com/u/88354667/fif_playertransition.mp3Now something I hadn't noticed that I'm not certain has been brought up is the middle position on windows that Felix can reach via jumping. This is necessary for situations where piles of bricks are dropped side-by-side. It can ONLY be achieved through jumping, and does not provide protection from bricks that would fall and hit Felix on either the left or right side of the window.
After losing a life, Felix will appear on the bottom window of the column he died on, in the CENTER position. This is unlike the level entry, when Felix jumps on the right side of the right-most bottom window.
--> Necessary for -->
Also, I did run into a minor visual glitch where a Nicelander began to leave a pie in the window right as Felix was fixing it. The sprite continued to appear in front of the solid white of the fixed window, followed by that of the pie. It really doesn't affect anything, other than the fact that you don't have to repair the window you get the pie from.
Finally, a video of the attract loop. Again I wish I had a camera that adjusted well in shifting lighting, but if anything it could be useful for timing purposes.
(Video may be processing for a bit)