For Opera, I would recommend the Breeze Simplified Micro skin,
here. Using Opera click 'download skin' and it will automatically skin itself for you. If you don't like it you can always search for other skins
here.
By right-clicking on any part of the toolbar you can click 'remove from toolbar' (pretty self explanatory).
Also, tools > appearance > toolbars
I have status bar, address bar and tab bar ticked. If using tabbed browsing (which i recommend), make sure the tab bar is selected (yellow box will appear around it) and tick 'show only when needed' so if only one page is open the tab bar will be hidden, increasing screen space.
With all toolbars you can choose their position; just make sure they are selected and choose top, bottom, left or right.
tools > appearance > buttons
browse through and drag any additional buttons to where you want them.
Unfortunately the file, edit bar must be seperate, ie. no other toolbars or buttons can be on that line.
example screenshot: