I guess just from Surfer always being tied to Thanos, I had always assumed Thanos could also wield the Power Cosmic, and did so in his battle with Surfer and others.  I just read through Hunger's CV page, and I noticed that Thanos had to ask Galactus to use the Power Cosmic in an attempt to defeat Hunger...and I was like what? Why couldn't he just use it himself?
 
So where does Thanos get his ability to shoot energy blasts and achieve other effects, if it is not the Power Cosmic...?

He is a Titan Eternal. They all have powers. His deviant gene apparently raises his power.  
 
Through mysticism and technology, he has raised his power even more. Now he is the avatar of Death and his already incredible power has been raised even further.  
 
Thanos has cosmic power, not the Power Cosmic (although one instance said so, I take it as a writer error).