Since (IIRC) CodeLite 13 the preferred method of code completion isbut code completion still not work.
Language Server. Maybe that wasn't/isn't active in your configuration: check 'Plugins > Manage Plugins: LanguageServerPlugin'.
IIUC installing your own clang shouldn't have made any difference to whether that works or not; and using clang to compile your project certainly wouldn't have.
I'm not sure I understand what you mean by that, but: look in Project Settings: General > Execution. Is the 'Pause when execution ends' box ticked?The only downside with Clang is the compiled binary when run via CodeLite doesn't pause for me to see the output like the GCC one, it closed almost immediately.