I believe the only schema you want in the SYSTEM tablespace is SYS (you should check your users temporary tablespaces as well - they should all be in TEMP). We have our System in TOOLS. I believe OUTLN, DBSNMP are part of interMedia and should go in DRSYS. Check out note: 1015980.102 which explains why DR$ indexes show up in SYSTEM tablespace - the index in SYSTEM tablespace takes no storage.
It depends on whats options you want to use. I had a tar on the same(not exactly same issue, but implications of changing default users pwds as a part of hack proofing our databases) with oracle. They were not sure, Finally they said to save the default pwds and change 'em. In case you want to use that option in future, it may not work though you reset the pwd using 'alter user' syntax. You have to run the saved passwords script to put 'em back. Thats what metalink says. Follow this interesting link for further information.