If you use the secret phases, you will go faster. Do you know about them? I can teach them to you for small fee (€500).
No dice, you should try your luck and ask the user who submitted for the video.
You can no longer downgrade to 1.0 on GOG, if you got it on steam however you can.
Actually this version of beppi skip (where you go straight to the 3rd phase and the ducks stay on screen) is possible in 1.1. I myself have got it a few times but wasn't recording. It requires ludicrous amounts of damage, where you doing 3 or 4 more doubles after you get the smoke particles in 1.1. I haven't managed to replicate since but i'm sure its there. If you only do a bit more damage in both 1.1 and 1.0 you still get the unreachable head but this requires alot more.