1) What do you think about these parts?
Those parts should be fine but if you're considering putting SLI cards in the loop, maybe consider going with a 480 RAD.
Also, that is not a kill coil, that is a coil used to prevent vortexes in your reservoir. A silver kill coil is literally a little chunk of raw silver and is unmistakable for what it is.
2) The thing that confuses me most is the reservoir,...
It seems like it can work either way but it looks like the hole with the little tube extending into the reservoir should be used as the inlet. If you put the three ports on the bottom, it won't matter too much but if you put the three ports on top, the tubed-inlet will extend down below the waterline and prevent the "waterfall effect", which can put air in your loop and it will also help keep air from backing up into your loop when you turn the pump off.
Also, the fill port should always be on the top. If you mount the reservoir with the three holes at the bottom, you would want to make the inlet and outlets attach to the bottom and use the single top hole as a fill/drain, whereas, if you mount the reservoir with the three holes on top, you'd use the bottom hole as an outlet and then you could use the top hole with the little tube as the inlet and one of the other two holes as a fill.
I would also like to know if people use the fill port as an inlet.
Typically not. The inlet should contain water pressure at all time so it would be ill advised to disconnect it for the sake of draining/filling. The fill port should be separate.
I want to put my pump next to the PSU, below the reservoir ...There's nothing to push the water to the pump if I fill it from below.
You would not want to fill it from below and this is why you will want the fill port at the top of your reservoir so there is always water pressure going to the pump.
3) Any advice on the loop order?
The only rule you need to follow is to have the reservoir above the pump so gravity will maintain water pressure to the pump.
4) Can I attach to the radiator 3 SP fans to each side or would that prove useless?
You won't get twice the cooling but it will provide more cooling than if you just had fans on one side of the radiator. Usually, the biggest obstacle with this configuration is if you have enough room for this amount of hardware. since you have the 900D, you should be fine.
5) Do I need in my loop drain port and fill port?
You need to factor in how you're going to drain and fill your loop, yes, but you don't need a "fill port" per-say and people drilling dedicated ports are only doing that to be fancy. Typically, you'd use your reservoir to fill your loop. You will fill your reservoir and it should fill down to your pump and once you fill up your reservoir, you briefly run the pump to move the water farther into the loop. Repeat that process until the entire loop is filled with water.
As for draining your loop, this is a lot trickier. The best way to do this is to use a dedicated drain port but the drain can be integrated with other components. The best drain port is located at the lowest point on your loop so gravity will aid in draining the port. For example, I use my fill port on the top of my reservoir to drain my system. I attach a long hose to the top of my reservoir and then turn my entire computer onto its back and that port turns into the lowest point of the loop.
http://oi62.tinypic.com/akiero.jpg
To effectively drain your system, you also need a "bleed" port at the highest point of your loop to allow air into the system. otherwise, you'll experience a suction, similar to how a syringe works and your system will drain extremely slowly, if at all.
6) It's a little off topic but do you reckon it's better to get the i7 4930k and water cool that instead of...
That's up to you really. If you have the money, go for it but the i7 4930k is still a good CPU and the the x99 platform is still very expensive just for the fact that you're using cutting edge technology.
One last question, I'm looking for fittings now and I'm not sure how to choose them properly.
Fittings are best chosen once you know how the run is going to work. If you want to draw a mockup for what you want to do, I could help give you pointers.