MC Source and MC Source Distribution!?

[Mecblader]

Hello, I want to create a game changing mod and I know that changing MC Source is a big no-no, but would you think it is acceptable if it is a game changing mod. Also, would i be allowed to distribute my mod with edited src code in the zip. it wouldn't be the whole game, but some parts of it. I would appreciate any help I can get, I just don't want to get into trouble with mojang. Also my mod does not need to be compatible with other mods, my mod would change the way or purpose of Minecraft.

[Mecblader]

Is there some sort of method that I can tap into to detect when the player breaks a certain type of block. From the link that was provided I saw that there are special events that forge provides. Could you please explain what they are and how I can uses them and any other way I can go about making the mod without editing base classes and using advanced java to change code while the game is running, thats what the ASM thing does right?