Please post error reports in the MusicCabinet thread (
viewtopic.php?f=8&t=9504) if you run into any trouble with the Android client, with steps on how to reproduce.
Be sure to use the latest version (0.7.10), the early 0.7 versions had some issues with mobile clients, but as far as I know, those are fixed now.
The mixing of folders might persist though as the browsing is tag based, not folder based. That means your artist names are displayed in the interface, not your folder names. Cover art from last.fm that's used in the web interface is not used in the mobile clients, they only use embedded artwork / folder.jpg etc. If your library is horribly tagged, some files might be ignored by the media scanner (files lacking either artist or title tag) as the scanner has no way of knowing what music that actually is. Warnings about such files are written to musiccabinet.log during initial scanning.