shieldbug1

The NEI API is documented and should be sufficient. Look at the API class to see where to start. If that's not enough take a look at another open-source mod that implements this feature, and see how it does it.

Looks like an ID conflict: Long story short, update to 1.7.10

Both 1.7 an 1.8 have almost complete mappings, just use the daily snapshots. I haven't encountered any bug or glitch that makes 1.6.4 better than either of those versions. There is nothing but performance improvements in the newer version, I haven't experienced any framerate drops.

World as in server/thing you click in the world selection menu.

1. Use the item's onUpdate method, since you're checking for your item 2. Don't use LivingUpdateEvent for players, the PlayerTickEvent is for that.

ID's don't change per world. So if you have to store something in one world that will never need to interact with another world, use block and item IDs. The preferable method, however, is to get the names of Items and Blocks from the Item and Block registries respectively.

Post the crash log?

Update to 1.7.10 or read the EAQ.

Just a bit of a tip - you can use newer mcp mappings to get better naming. Nearly everything has been named by now in the daily snapshots.

... What. -facepalms-

First of all, why is your damage variable static? Read up on what static means. Next, where do you call changeDamage()?

Post code.

http://lmgtfy.com/?q=How+to+rename+a+file

The Block Registry is exactly what you should be using. Block.getBlockFromName uses the block registry itself.

You posted the same class for your TileEntity, Block, Gui and Container...