Since you mentions the minigames houses I would love to see Mario and Luigi according to the transformation they have at the moment, the original game only shows us Mario (Luigi), Super Mario (Luigi) and Mario (Luigi) Raccoon. Missing (Mario and Luigi) Fire, Hammer, Tanooki and Frog (For these the original game only employs Super Mario (Luigi)). I know that you do not have the ability to do this but it is possible that you include it in the requests list maybe someone is interested in doing so and can redirect the appropriate image of Mario and Luigi according to the suit they have at the time.
Something that if you can fix in the mini games house at the moment is the image of small Mario and Luigi they need white gloves and if possible fix their eyes and put the white part
I think we can assume that if I make a change to one sprite, i'm going to try to make it universal across all sprites, but to answer your question, yes.
It's slightly based on my Big Mario sprites since that's basically what they did in the original game. I don't know if i'll change the "Big" Mario sprite for minigames beyond giving him blue eyes and the yellow soles on his shoes, we'll see.
I'll add your other suggestions to the OP. I don't know if I want to add too much more to the OP because at this point I feel like i'm asking people to do more work than I am.
I like it!
New toad looks good too, though it seems you've simplified the shading of his head a bit so it's a tad flatter.
See above, better?
Haven't had much time to work on sprites recently, though aside from player sprites and things I need to wait for the build script for, all that's left is polishing, there's very few unedited sprites left in the game aside from a few blocks and items I don't intend to change... also SMB3 items but I think I need to find a more organized approach for that, I can't tell where any of the items are used when I'm editing the combined GFX.
EDIT: Wow. New Super Mario All-Stars for NES hack on the front page has Mario Bros. Classic. Now I really wish I could squeeze an extra game in there. I can dream.