My user level: noob-ish, so please bear with me

I'm running 12.04 LTS. I have installed and, to some extent, configured xmonad 0.10

The "automagically" created xsession for it works fine as it is, but when I login it won't run a startup script I've created and "call from" /usr/share/xsessions/xmonad.desktop, if that's right. I've read pretty much all I could find about .xinitrc and .xsession, I tried that and it somehow messed up the other "sessions", if I'm explaining myself correctly. Had to $unity --reset to have the "main session" working again.

Anyway, my question is, how do I autostart xmobar and set a desktop background after login into xmonad's default Xsession?

I tried this script, start-xmonad:

#!/bin/bash
#
#I only used one of the following each time I tried, none worked
#Also, do I really need the '&'? I know what they're for, but...
nitrogen --restore &
feh --bg-scale ~/Pictures/picture.png &

#Then I want xmobar to start, again do I need the '&'? I know it's for it to run
#in the background, but I tried removing the '&' and xmonad still launched
xmobar &

#Finally, the only thing that seems to work in this script
exec xmonad

Yes, I made sure I did chomd +x ~/start-xmonad

The xmonad.desktop is

[Desktop Entry]
Name=XMonad
Encoding=UTF-8
Comment=Lightweight tiling window manager
Exec=/home/myusername/start-xmonad
Icon=custom_xmonad_badge.png
Type=XSession

So, this didn't work, now I'm here. Please help :s thanks