How to clean my Flash QE 25

I'm kinda new to airguns and have a few questions about cleaning.

First off, is it a good idea to clean your airgun before shooting, and is there anything bad that can happen to your gun if you don't?

Second, since I really cant use a traditional cleaning rod in this gun, I tried feeding some heavy test fishing line down the barrel with a patch attached, but since the line is curled, it keeps getting caught in the moderator at the end of the barrel. Has anyone had this problem and how did you overcome it?

Third, about how often does everyone clean their PCP guns?

Fourth, what about cleaning pellets? Do these work and are they worth the money?
 
I clean the barrel in my Hatsans when accuracy falls off about 500 shots. Always clean a new barrel before shooting. Lots of oil in the barrel from shipping. You can stick a straw down the end of the barrel to help get by the moderator. I always remove my barrel for cleaning. I find it to be easier to clean once removed from the rifle and shroud. 

Have fun!
 
Like seth said get a straw. I like mcdonalds straws. Slide it inthe moderator gently. Dont force it. Instead of fishing string try weedwacker line. Heat up the end and push it down to make a flat area your cleaning pads can stop on. And then feed it thru the breach and out the muzzle. Works great.

Edit. Just pull it slow and straight.