Theme

Copy the WIN7LIKE_COMBO_revE.skin7 file in the Open Shell skins folder.

Open the Open-shell settings, in the Skin tab (1), select the custom theme named WIN7LIKE COMBO revE.skin7 (3) in the select (2).

Icon

Copy the Start_Button.png in the Open Shell folder.

Open the Open-shell settings, in the Start Menu Style tab (1), check the Windows 7 style is selected (2) and then click on the Pick image... button (3) to choose the png file you pasted earlier.

In the Start Button menu in settings (1), check the Custom button is selected (2), and you can change the Button size to 60 (3).

Result