Allow me to answer, even this is my first post
MySQL Query browser is tools for the database, check, delete, rename, even drop the table, etc2. It is enough, just download MySQL Query Browser.
The purpose of Xampp is to emulate your own hosting on your PC, in other words is making your PC act like a web server, so you can emulate server in your PC. Example, you want to create website, you need Xampp to create local-host on your PC. Basically Rathena is emulator for Ragnarok server, means you need local-host / web server to run the emulator itself (Sorry for my bad English). Hopefully this can answer you questions.