You will get a gray dialog box with some options of what to do with that file. Opera 3.5 supports the Sun Java plug-in. This is the 32 bit version of Opera only, and the plug-in is quite large. Funtionality is the same. Currently, there are no differences between the 32bit and the 16bit versions of Opera.
Opera does newsgroups only online.
There's no way of offline reading other than from the cache. There's currently no way of specifying an external newsreader. Opera cannot receive mail at the moment, but we are working on it. Opera doesn't yet include a dialer. We would like to include one with the 16 bit version of Opera.