Is there any shortcut for CodeBlocks to format the code?

probably not by default but you should be able to assign it there:

Settings -> Editor -> Keyboard shortcuts -> Plugins -> Source code formatter (AStyle)

My favourite = Ctrl + A then Ctrl + Shift + F.

You (these are the default settings I believe) can select a block of code and press the Tab key. This will indent the entire block.

So for indenting a whole file: Ctrl + A, then Tab.

In addition, you can use Shift + Tab on a selected block to "unindent"

You can move through the open tabs with Ctrl + Shift + Tab.

As for the best shortcuts:

I like Ctrl + D to duplicate a line and

Ctrl + L to copy it.

Anyway, you can set whatever shortkeys you like in the Editor menu (there you will also be able to find all shortkey currently set).