1) No, make a new folder (ie: c:\EQEMu)
2) When you extract the 4.1 emu, it will have a folder called ItemEditor, the exe is in there
3) Windows and Linux both work
4) You can 't play the emu till they fix it, this last patch broke it
5) Again, the last patch broke the emu, but you can still create items, you just won't be able to test em. Read the
readme, it will tell you how to set up the database, once you do that you can use the item editor.
No ETA for when the emu will work for the jan 9th patch, so please don't ask and be patient, it will be worth the wait