Gheeez!! you'd think more info would be here... Anyway, I just started using CloneDVD mobile and I believe that it uses the codec that is already installed on your machine unless that happens to be an older codec than what comes with CloneDVDmobile. As far as the XviD choice, I have no clue as I'm currently only using DivX and I don't remember seeing an XviD choice in the initial menu selection.
As far as the Audio, you might try looking in your control panel for an AC3 Filter entry. If it exists, just click on it and you should get a fairly extensive configuration panel. If not, try downloading the attached file and installing that. I had some problems with some other converter programs and audio issues so I installed this AC3 filter and adjusted a few things and my problems went away. Don't know for sure if CloneDVDmobile uses this filter, but it shouldn't hurt to install the AC3 file to make sure.
Couldn't upload the file, but you can get it here: http://prdownloads.sourceforge.net/ac3filter/ac3filter_0_70b.exe?download