First custom loop, need help.

Have you read the sticky?
http://www.tomshardware.com/forum/277130-29-read-first-...

I would go for the separate pump and reservoir option, in my experience bay res/pumps are loud since they vibrate in the bay.

To figure out if the rads you have picked will be sufficient for the components in the loop, you have to calculate the sum TDP (Power draw) of everything cooled by the water and compare to what the radiators can dissipate. Make sure to pick reasonable fan RPM values when deciding on the radiators ability, a rad might be able to dissipate 300W, but you aren't going to be running a fan at 2000RPM to achieve it, way too loud.
EDIT: On radiators of the thickness your going for, will want some very good fans to go on them.

Fittings and tubing
There's a section dedicated to this in the sticky, it will explain everything.

Other Misc stuff.
You will need something to stop bacteria and Algea growing in the loop, there are two common options with this.
- A Kill-Coil, basically just a small strip of silver that you drop into the reservoir or somewhere it can contact the water. It will ionize and kill bacteria/algae.
- A Biocide, a chemical (usually Copper Sulfate) that kills the bacteria/algae.
Then there are others like UV light and Ethelyne Glycol (useful if ambient temps can go below zero, acts as anti-freeze), but most don't use them.
I personally use a Kill-Coil since its less hassle than Biocide, don't have to re-apply whenever I drain the loop. Its just a drop it in and forget it type solution.

Your probably wondering about what coolant to put in, and the answer is plain distilled water. Get whatever distilled is available at your local supermarket, once its poured into the loop it is contaminated by the metals of the blocks and rads, so it doesn't matter how pure it is before it goes in so there's no point in buying "quality" distilled.

Yes, I read the sticky, but still confused on what to get, as for TDP.
CPU is 130w TDP stock, I'm guessing probably 230w overclocked
2 Titans: stock TDP 250w, but will be overclocked so around 300-330w each.

Thanks for the input so far, the rads I got help from other Cosmos II users when I picked them, but even after reading about fittings, I don't know which ones to use as well as the tubing.

So, you think the 2nd option of separate pump and reservoir will be best?

About the fans, i have about 12 CM excaliburs on my case i can reuse, but looking to use Red Led fans for the aesthetics, any good ones?

The sticky explains how to calculate loop TDP for your components...it even has detailed examples on how to figure out CPU overclocking...as well as a link that will do it for you. As for TDP of overclocked GPUs- are you changing voltage or simply bumping the clocks? If the latter, TDP won't increase as much as it would if you change voltages.

You have the D5 pump in both the bay res and the res+top...it's the same pump in both scenarios.

BTW...this is only a D5 top, not a pump: http://www.frozencpu.com/products/17626/ex-pmp-217/Alphacool_HF_D5_Top_-_Laing_D5_MCP655_-_Black_Acetal.html

As Rubix pointed out, there is an explanation on how to calculate the TDP in the sticky. There is even an equation to figure the CPU TDP after overclocking.

Fittings come in two flavours, barb and compressions . Both do the exact same thing, except compression's look a bit better for a few dollars more.
Then you have things like 90°, 45° adapters and rotary ones, and other misc stuff like T-Blocks. But just having a look at them should make their use apparent.

Yep, I think the separate pump and res option is best. As Rubix said, no performance difference between the two options because its the same pump, but I have found that bay mounted res/pumps vibrate against the chassis. Because there is little room around it, very difficult to pad it to reduce the vibration.

I think Silverstone Air Penetrators come with red LED's.