OMGGG an article about my remaster project, that's so cool! Thank you so much!
If I were to make a Remastered Mode feature tweaking system, I'd probably make it an extra submenu in the settings to be honest. I'm not sure yet, I'll think about it but I can't guarantee I'll include it. As for increased ruby drops... I'm not sure. It feels a little more like a cheat code to be honest. Nothing wrong with that I suppose, but I'm not sure if I'm 100% on board with that. The things enemies drop are currently completely random. Either they drop 5 rubies, 20 rubies, a heart or nothing. I don't want to make the game too easy or predetermined if that makes sense, but I understand the frustration.
About the question at the end, part of the code has been extracted by discord user Phlosion, which gives me information about how much damage attacks and enemies do as well as the defense of the player and enemies and the bonus damage weapons do against enemies.
One thing that is also very important that the extracted code includes is the movement patterns of shrine bosses, keese and walking NPCs, which I had to guess before, and it was a mess to figure out back then.
Apart from code, he also extracted a bunch of textures and turned the palette cycling image data (to simulate streaming water for example) into animations so I can import those easier. Dialogue was also extracted by him, though music tracks (intros and loops) were extracted and organized by MundyC.
For the usage of the weapons however, I basically have to replicate how the projectiles move by watching footage I record of the original game. For enemies I have to more or less guess a reasonable hit range. I'm also redrawing every collision texture (the originals were sloppy and didn't reach the edge of the "tile") and cutting out the foreground objects by hand.