Blashmet, I do not know what you know about the Windows registry. It has a good name of doing automatization. It has a very bad name as buildng up a lot of a rubbish in it, very bad documented on all vaules an options. Changing names and locations by releases. This is life at the hard-core system level.
1/ Probably Oracle could deliver a reg file for disabling the java plugin, you should ask Larry.
2/ See the note to registry contents, you cannot really trust that. Unistalling is trying to clean that up. Do a research on your contents (regedit).
---->-- ja karman --<-----