One more question... do I need to buy anything special for the layer beneath the jacket? Or will a normal jumper be enough? :P
It all depends on the temperatures. For me personally this is how I break it down for varying temperatures
<23F: gortex shell, light down midlayer (patagonia nano puff), shirt, thermal (ninja suit)
23-30F: gortex shell, polyester hoody, t-shirt, thermal (ninja suit)
>30F: gortex shell, t-shirt, thermal (ninja suit)
For the bottom half I usually just wear shorts over my ninja suit but if it's really cold I wear a fleece long sleeve.
A nice thermal goes a long way. You just need to layer up according to the temperatures, nothing special is really needed. Once you get experience you'll start to get an idea of what layers feel right to you. Just don't wear cotton clothing because it retains moisture.