No version deferent and ya to everything else

I think New3DS is 11 seconds faster but it's not that big of a deal

maybe I don't know

The main difference between the games is the 3DS you use, anything newer than an original 3DS, such as a 3DS XL, New 3DS XL, or a 2DS all have the fastest loading times, Japanese is the fastest version of the game due to one less textbox in the first mystery box
Filming the game with a camera and retiming is fine as long as it's an accurate retime