its there, you're being stupid and trying to install the source distro without reading the readme.
Want a install guide:
Download universal
Copy files in minecraft.jar
Done...
Nothing off the top of my head, but take a look at the EntityTracker* classes, those should contain a list of players and the entities they are aware of, {or inverted} but that would be the place to start.
Doesnt matter if you mover it in or MagicLauncher does
its the same thing.
Something you're using screws with Minecraft.class in a way that should not be, and crashes, doesnt seem to be a forge issue.
You need to use TileEntite's packet to tell the client what it should of read from the NBT.
As the client doesnt store the world file anywhere it relies on special packets to describe what tile entites are to it.
This has nothign to do with Forge, its just you havent written your TileEntity fully.
Doing instanceof of is a really really bad thing you're making a hard dependancy on the other mods.
What you *should* be doing is checking if the class name equals a string, or something to that effect.