Calling on those who have used the Graco paint sprayer

Hey guys. Well, i got my No name paint sprayer( which in fact turns out to be Graco,awesome brand), and have used it and need some input from those who have used it.
So i sprayed another layer of Behr SS/delta white pearl mix on my current screen. I have question so i know my gun setting are right and so forth.
While using the gun( this things BLOWS AWAY my old paint gun), I did have some paint spitting out. The Behr SS mix paint that used, was sitting in the shed so the paint was cold and probably had some solid junk in it for sitting so long so that might have been clogging it. I did stir it before using it to mix everything again. Also, the level of paint in it might have been causing it to spit. Which leads me to my next question, which is: How does the amount of paint in the Paint Container effect the spraying. I've noticed with other guns that as the level of paint gets lower in the container it starts to splatter and spit out of the gun.
The Spray pattern coming out of the gun wasn't very big either. I did have the setting set to Left and Right spraying but the stream came out small. When i sprayed water out of the gun, while cleaning it, the spray was nice and big verse the size of the paint. Again, this was probably due to the thickness of paint.
Third, when it comes to the little wheel you can turn, known as the Paint Flow Adjuster, that sets how much paint will come out by pushing the needle in or out, are you supposed to be able to turn that knob all the way so that NO paint comes out and you can't push the trigger at all??? It seems that when i got the gun and was checking it out I don't remember being able to completely turn the knob as such when i first got it but not sure on that. I'm hoping i didn't mess something up when removing the Stain/Latex needle assembly the first time I did so I could see how this bad boy looks disassembled.
So, anyway, Is my knob setting okay and the complete shut off of paint coming out okay?? How does the amount of paint in the Paint Container effect how the paint gun works?? Thanks guys.

I wasn't to concerned about using this gun, on this mixture. The splatters that did spit out were solid and i was able to just pick them off with no effects on the screen. The Gun did a wonderful job, even with those few issues, on spraying the screen. I'm not able to see any of the defects on my screen when the projector is on so it's now prob. I sprayer the final coat on just to use the gun. Wasn't worried to much about how it would come out because i tested the gun out on another surface first and did fine.
I just mainly want to make sure the Paint Flow adjustment knob is made so you can completely shut off the paint. That when you try to spray none can come put.

Sorry, I'm not always good in putting into words what my mind is thinking, lol. You answered all my questions Dennis with your message, thanks. I just wanted to make sure the gun was made, so that normally, you could completely roll it back so that the trigger is locked and no paint could be sprayed out.
The amount of paint I had in the Paint container wasn't very much so i was guessing between the low amount of paint in the container and the lack of the use of a paint strainer, was causing the spitting.
I'm pretty sure my gun isn't defective. I'll be using it again soon to spray paint our front door. I'll make sure to do everything right this time and I shouldn't have any problems.
Oh yeah, one finale question. When i was done spray painting, I followed direction with the manual and sprayed water through my gun to clean it good but After I disconnected the long Hose why did water come out of the Hose???? Did some of the water get into the hose or does it has something to do with how the whole thing works and the compression. Thought it was weird that water came out of it. The water was clear, not hint of paint in it. I don't want water getting into the vacuum. I was careful to make sure it didn't go backward into the vacuum when draining the tube.