Lua script:
http://pastebin.com/muF6ZwH8 (Edit: This is a new pastebin because the old one might not work)
How to use:
This script can do memory search to find the dynamically assigned speed and angle addresses (that change each room).
To unlock those addresses, walk left (with the emulator not paused and Yoshi not hitting a wall) and simultaneously click on the field.
You might need to redo the search a few times because it can sometimes fail.
(Thanks to ism because I used his lua code for memory search)
(Thanks to masterjun for helping me with the timer)
I don't know if I will run this game again soon. Hitboxes and object info (how gravitation affects them, swingboat speed etc.) would be useful to add to the lua..
Please note that the gold medal objectives are only filled in up until some point in world 4. The remaining levels need to be checked for gold medal requirements.