The best thing to do to prevent yourself from asking questions like these is to search, search and search again, and maybe if you can't find the answer then ask a question. But here's a few hints: First read the wiki on overclocking, you need "kernel power" to overclock/undervolt and you'll find the latest stable version in the testing repo, there's a newer version in the devel repo, but don't use that unless it has a feature you really need.