The Control+P and Control+F keystrokes have been around for a while,
certainly since Sibelius 3, although I think the Control+M keystroke was
added later. 

What's actually happening is that you're typing a shortcut key. If you read
through the items in the word menu you'll find a shortcut key after a lot of
the special symbols and characters. So, pressing Control+P twice is the same
as opening the word menu, selecting "P" and pressing enter - and then
repeating the operation a second time.

Two other useful shortcuts are Control+Shift+C and Control+Shift+D which add
the text "cres." and "dim.".

It's H for crescendo hairpin and Shift+H for diminuendo hairpin. 

If you need one of those silly little phrases, try:

extend a single hairpin until the next expression mark, rather
than one per bar.  That's how it's usually done. 

As a rule of thumb, only use a hairpin if the crescendo is two bars long or
less. For longer crescendos add the word "cres." using expression text. The
same is true for diminuendo hairpins and the text "dim".