You're welcome!
1| There are a lot of reasons why a person may want to go into watercooling, dimming down the noise may be one of them but beware, the perception of noise and its definition varies greatly from individual to individual. I stated this because the GTS Stealth seems to have a high FPI count and from what I can recall that rad needs high rpm (high static pressured) fans to keep temps in an acceptable range So this would defeat the purpose of cooling for silence approach.
2| Another aspect of watercooling(who do it) look into the performance aspect of the hobby if you're looking into this field as well then the MagiCool Butterfly isn't well performing, may want to check out the (popularly used) XSPC Raystorm block that goes for ~$50 on sidewindercomputers or Performancepc.
3| Like I mentioned earlier tubing needs corresponding barb or compression fitting dimensions to save yourself from a world of headache and possible dead components from leaks. You may go for slightly larger barb fittings than your tubing but otherwise its not going to work the other way round. I mention this because you've mentioned G1/4 barbs. that is the thread of the barb fitting, not the end that connects to the tubing.
^ covered in the sticky ind you.
4| Cramming all that hardware inside the case can not net you desirable temps, I'd ask you to consider mounting rad outside of case where you can allow your fans to draw cooler ambient air into the rads and possible allow you to run in push/pull setup with some fan shrouds.
5| At a glance you've made an attempt at watercooling but have managed to hit some unwanted problems one of which is buying a slim rad that must warrant noisy fans.
In a nutshell watercooling is a hobby(maintenance) with aesthetics(parts variety), performance(thermal dissipation and overclocking), time(assembly) and expenses all rolled into one. When you realize you've spent more than you needed to get the desired output then the whole endeavor seems demotivating and at the end of it all you'll notice a high end air cooler would've been the best route for all your efforts
So what are you trying to accomplish with watercooling?
Have you considered getting a kit while returning the rad you just purchased?