The first one is removing the gap between the "Command Bar Background" and the "Top Glass Area" in Windows 7. ( I've pasted a link below of a screenshot of the problem.
That is actually your toolbar background. A little bit of it shows when you have it hidden, All you need to do is skin the background to the desired color.
Edit Controls/Edit Toolbar Controls/Rebar Controls/Background
how do I change the colour of the light grey in the red square to match the top little bit of grey circled in blue in this screenshot.
That grey is your Button Face color in the colors section.
Change Skin Colors/Show Me The Skin Defined System Colors (in the dropdown on top)/Button Face Dialog Background Color.
Be warned, changing this color will change it in lots of places in your skin.