These might be useful
Also, regarding your specific questions about keyboard shortcuts, most commands on a Mac are accessible from the Menu Bar. If there is a keyboard shortcut for a command, it is shown next to the command in the Menu Bar. For your example with New Tab in Safari, it is under the File menu (and it's Cmd-T). So you can look in the Menu Bar for the keyboard shortcut of frequently used commands.
Also you can see the general keyboard shortcuts. Under the Apple menu (in the Menu Bar) select System Preferences. Go to the Keyboard pane, then to the Keyboard Shortcuts tab. There, you can see current (systemwide) keyboard shortcuts and change them (if desired). You can also add new shortcuts, by clicking the plus sign.
Safari browser and menu shortcuts:
Mac OS X keyboard shortcuts:
Changing behavious of Function Keys:
and more useful information on keyboard shortcuts here:
Switching from Windows to Mac: