Instead of Control use the Command Key (⌘). So Ctrl-C becomes ⌘-C on the Mac.
First of all, if you plugged in a Windows keyboard, the Start button acts as the ⌘ key.
The Undo shortcut is similar, ⌘-Z however the Redo you need to hold the shift key while doing ⌘-Z.
The hash/pound # key
To type the hash / pound # key, you need to press the Alt together with the 3. I got stuck on this when I wanted to do a #import :)
In Windows Ctrl-arrow keys would navigate the text word by word. On the Mac you need to use the Alt instead of the Ctrl. (Luckily on XCode, the Ctrl shortcut does the same thing). The End and Home keys will take you the very end and start position of the whole text. Very annoying since on Windows we are used to be related with the current line being edited. To go to the end or start of the line you need to press Ctrl together with an arrow key.
Quick Dark Scheme
In Windows I use WindowBlinds and my Dark Aqua scheme, (inspired from the Mac). There are some skinning applications on the Mac, but I haven't found what I'm looking for to be able to switch completely to a black skin. However there's a quick native shortcut which will invert the colors, and so if you feel that your eyes are getting strained during those late night coding hours, you can easily switch to a black scheme by hitting Ctrl-Alt-⌘-8.
You can either launch Activity Monitor to replace Task Manager. Or you can launch the Force quit menu by pressing Alt-⌘-Esc.