1) No, you don't
2) They contain different language packs:
Top Sony - Languages Description
3) Yes, it should ;)
4) This is the Revision number. It has got nothing to do with your firmware version.
Just look at your log, you've got an R10A custpack with R6BE001 firmware ;)
You can use CDA102568/15 or /106, they're both generic.
Top Sony - CDA W580