Tascam US 16x08 Mixer Recommended setting Sonar Platinum 2016.08 for vocal singing

Any chance you could post a screen capture of your Output Setting tab?
 
Here's what the default looks like.
 

 
Re the noise/clipping, one possibility (and why I want to see your routing), is that you're summing audio when you don't mean to.
 
I use this tab only when I want to just play my guitar or bass (through Inputs 9 & 10) directly to my monitors, without involving SONAR. Once in SONAR, or any other DAW or audio app, this feature is basically useless.
 
I'm not clear on exactly what you're trying to accomplish, and why you're not doing the sub-mixes and routing in SONAR.

3. Playing prerecored project there is a lot of noise cause the gain is so high and getting in the red area on nearly all audio outputs what´s the best way to handle that.
 
uuh, turn it down...