Re: OOC2
In GURPS terms, prone is lying face down. You can also lie face up. I don't know how Gurth sleeps, so I'm just mentioning that in passing.
The monster is not close enough to Attack Gurth, but it's close enough to Move and Attack.
It is facing Aladin, which likely means that it has its side towards you.
The knife Gurth has is a large knife, not a long knife. So that affects its stats. This is fortunate, as long knives aren't effective when thrown, but large knives are.
And from what I can see, there are no penalties from throwing while prone, as long as you are facing the target.