no, repairing leaves the settings (even corrupt) also intact. Repairing just repairs your executable and DLL's to their original states (before you screwed them up with patching or something). Settings are left alone...
uninstalling and reinstalling does exactly the same. The only difference is that if you uninstall/reinstall, all the files are deleted first by the uninstall process.
I dunno, because you did something wrong, forget to do something? The difference between the two is as I stated though... Anyways, important thing is that it is fixed