For both the sound and ugly theme you can run 'gnome-settings-daemon' to use gnome settings (it will use your gnome theme and sound preferences). If you don't want to run an extra process:
1. for the sound issue try this: in /etc/X11/Xsession.d/ there should be something like 52-libcanberra-gtk-module_add-to-gtk-modules. (Re)move that.
2. for the themes: either install and use lxappearance if you want easy or create a file named .gtkrc-2.0 yourself (with the dot to make it hidden) in your home folder with your favourite text-editor and make it look like this:
Use the exact theme names. The 'include' part is for if you want to make specific changes in your theme; it's like changing the gtkrc inside the theme folder. Not necessary.
Edit: I found that for the sound issue you can add the line
to ~/.gtkrc-2.0 (and maybe also the line gtk-error-bell=0 ).