|Shift s||Snap to centre|
|r,x,90||rotale 90 degrees|
|ctr-R||make round corners straight|
|g,z, 100||move on axes|
|More to come at some point|
If your objects middle is not in the middle. Try:
Press Shift + Ctrl + Alt + C (perhaps the longest shortcut in Blender) and select Origin to Geometry. Or, instead, open the Toolshelf by pressing T and press the Set Origin button in the Tools tab, subsection Edit.
Depending on how you imagine the 'Center' of your object, you might instead want to choose Origin to Center of Mass. The difference is that it calculates the center point based on the volume of the mesh, rather than the average location of vertices as Origin to Geometry does.