IMHO, I think the jury is still out as to whether life is easier with or without a reservoir. I've run my systems both ways, and while it is nice to have one less part to worry about, bleeding the air using a T-line is a real pain that takes hours, and can involve rocking your system back and forth to try and get all the air bubbles out..
I think it has to be personal preference here. Reservoirs make it easier to fill and bleed your loop, as well as topping off your fluid when it gets low, while a T-line has fewer parts and less fluid in the loop.
Push/pull has to do with the radiator, where you have one fan (or set of fans) on one side pushing air through the radiator and another fan (or set of fans) pulling air through on the other side. It is one way to assure that as much cool air gets to the surface area of the radiator fins as is possible. To eliminate dead space around the cone of the fan (where the motor is), you can use a radiator shroud to space the fan 1-2 inches away from the radiator. This is most effective when used as an external radiator.
The push/pull designation comes from several airplane designs (old and modern) that used two engines in the front and rear of the aircraft to push/pull the air over the aircraft.
Okay assuming you have an average cpu and graphics card with no overclocking settings. That would be from reservoir tank or T-split reservoir, then it goes to the pump and to the cpu, exiting out and going to the graphics card block, then goes to the radiator, then cool water comes back to the reservoir and repeats the cycle.
Or you can split the tube from the pump towards both cpu and gpu at the same time. This lowers the flow rate on the blocks but gives equal cool water and may have better cooling than the single loop I mentioned above.
For the radiator you can have fans on both side and facing the same direction. One fan is pushing air in to the radiator fins and the other is sucking it out.This achieves higher air flow inside the fins and do so with low to medium rpm fan thus operating silently. This is called the "push-pull fan setup".
You're quite right about what is better, I personally use a reservoir but can see the advantages to not having one.
OP: whether you have push pull depends on how much space you want to take up and whether you want to go internal or external with your water cooling... mines all internal and my gpu temps (SLI) still dropped from 80C at load to 40C at load on one loop with a 120.2 rad with 4 fans in push/pull.
Damn your one of the 5 winners of the Corsair Dominator Gold Edition rams!!!!!!!!!!! Oh man, that rams are so bling blingin' in your case.
Correct me if I'm wrong but you are Wun Keat Ding from Down Under.
Oh by the way are those two individual loops sharing one reservoir? One for cpu and one for graphics card, right? In your case I would just use triple rad and splits off to cpu and graphics card, that way less components. But your rig is bad ass nonetheless. Those RaptorX looks cool as well.