It doesnt reobf as _aux it just gets written it files as _aux and FML will load _ names before bare names.
So, this is till an installation issue on your end if you can't figure out how to install Forge manually, install it using a launcher.
FML is where most of the interfaces for event style things are. That design is all up to cpw.
As for the interfaces in Forge, the few that are left. They are there because they are better designed as Interfaces, not Events.
We use whats best suit for the job.
Please read your logs.
As for your issues with files being ope, you have a process somewhere holding them open, probably winrar or magic launcher, startup your task manager and kill them.
the issue is that you don't have the files properly installed or they are corrupt, either way there isn't much we can say beyond get a fresh jar and try again.
http://files.minecraftforge.net/ is our archive, it doesnt have 1.0.0 but whatever.
You'll have to find a old copy. We do not support old versions though.
Exception in thread "Minecraft main thread" java.lang.VerifyError: (class: mario/common/PacketHandler, method: sendRefreshDB signature: ()V) Incompatible argument to function
Seems like you've either corrupted your classes while installing or have a bad download. Cleanup and try again. If that doesnt work, go to the mod author and see if its there issue.
Dont use decompile.bat
Aside from that, it seems that you've either 1) not added your classes to the src folder properly or 2) ran updatemd5s which you shouldnt do.
Backup your code, clean the workspace, and try again.
That particular function should be fine as IIRC its just nooped out for the server.
However, typically if they are doing that they are doing a lot of other client specific things.
We cant unload the overworld as it would screw up a lot of internal things. the nether *should* unload if I recall correctly.
But none of the chunks should be ticking if nobody is there. So your cpw should be fine.
If not do some profiling and go yell at a modder for being excessive.
If the modloader mod does not rely on client only things it should work fine. FML does not limit ModLoader to just the client. Sadly, MOST ModLoader mods are NOT SMP comaptible.
This has nothing to do with FML, this is ModLoader and the modder are issue here.