Now, as for mkvExtractGUI and mkvcleaver. You need mkvtoolnix.
http://www.videohelp.com/tools/MKVtoolnix
Run MkvCleaver - the process is the same with MKVExtractGUI2, but let's go with cleaver for the sake of example. Click "Locate mkvtoolnix". Select the folder where it was installed. Then click "open mkv files to process". Select your mkv file/s. Then you'll have the file and an "audio" checkbox below it. Tick that checkbox. Click Extract Tracks, and you'll have a separate file with your audio. You're done. If you have many mkvfiles, tick the audio checkbox on the Batch mode column instead, that's all.