What may happen if I download Homebrew Channel?

I want to download the homebrew channel on my 4.3 U wii, and it is NOT UNLOCKED, I'm wondering that if i download it and later download the Riivolution application, am I going to lose any data? I mean, lose my saves or even my console, can that happen?

No, you will lose nothing by simply installing Homebrew Channel and running Riivolution; if you mess around with certain other apps (if it's on the WiiBrew Wiki, it'll have a "Modifies NAND" warning on the wiki page; if it's not on the Wiki, chances are it could be dangerous), you could potentially lose data or damage your console. And there is no such thing as "unlocking" a Wii.