you got it completely wrong, texture file must NOT be another terrain.png but with changed gold, just leave it completely blank and nicely (to a grid) put as many textures as you can fit (256 in total). In your occasion, you put few gold textures in 3 first tiles.
And yes you need property file for each block.
Aaand just watch greywulf's video tutorial, It's the source I used making this one.
I figured out that you don't need a giant changed gold ore thingy before I posted "Nevermind, Gold ore is 32" I just had the properties file named "terrain31" instead of 32. My texture pack on planet minecraft has it working now. It's called XDcraft. Thanks for helping BTW.
Yeah, Plenty_of_FIsh already answered the first two.
As for the third question, noone knows, I am kind of "scared" of that update, it's gonna change the way MCPatcher and OptiFine works from the scratch...
Yeah, It'll be really hard for mods that work with old default textures/texture packs to update... Well, It may not be THAT hard, but this method will definitely change, so will the methods for Optifine, MCPatcher, and any mods that use the old terrain/sprite index.
I'm trying to make a random texture for something placed down, even better if the 4 sides are diffrent. What is a good block to do this with, and what are some of the .properties? I've noticed the use of terrain and block; there's so mention of which to use for what blocks. Might be useful for "novices" like me.