Now when I look at the emulator file, I notice a lot more things... Turbo was used on the map screen for movign and entering levels, losing a lot of time. Left+Right was sometimes randomly released, no corner boosts, hitting the end cards late, bad HB RNG...
I just did a rough test that beats the first level 19 frames earlier, 5 of which were before the level started. I used 9X 1.51 for this test, but it's accurate compared to Bizhawk so far:
http://dehacked.2y.net/microstorage.php/info/101151414/SMB3%20Test.smv
There's is quite a bit to improve upon in the run afterall. Please share your videos so we can give you some feedback on it =).
As for 1ups: The way I did it in the 100% TAS was just to throw the shell, flip it and land on it at the same time, repeat. You can also check Genisto's glitchfest TAS of this SNES version, as he does a lot of this as well.