Those paint jobs look great!
You did the right thing getting the Iwata. When you clean it be careful to not "force" the needle forward or you will flare the opening on the tiny cone at the front of the brush and ruin it. Just push the need forward until it stops, no further. You should be able to shoot createx paints straight from the bottle without thinning at about 40 PSI. Make sure you clean the brush before putting it away and rinse well between colors. I use just hot water between colors.
Learn to listen to your brush............when the cone and needle are working properly the brush will sound like ssssshhhhhhhhhhhhhhh...............when it gets something clogged in it the brush will sound like skkkkkklshhhhhhhhhhsskshhhhskkkshhhh. There will be a slight "scratchy" sound instead of a smooth sound. If this happens you can grab that screw at the opening at the back of the brush and pull it back which opens the brush up and try to spray it out. If that doesn't work, which generally it doesn't, then take the back off, pull the needle, clean the needle off, then spray clean water through the brush. If it is still clogged then you need to clean out the cone at the front. I use a tiny dental brush for doing this, you can buy one at most stores near the dental floss, toothbrushes, etc. Hold the cone up to the light and look through it to see if it is clogged. When you reassemble the brush go easy! Be very careful with the tip of the needle, don't force the needle and go slow.
Enjoy!
jed