Fred500 sums up the state of the market pretty well. 240v tungsten has already vanished from a lot of shelves and the price of cfl's has dropped like a stone in an attempt to promote their sale.
Bear in mind that with a new build installation you should already be installing a proportion of low energy lights to conform with Part L of the building regs.
what you ought to think about is what you want to light and how you want to light it. Its all very well investing in a scene setting system but if all your doing is controlling a rash of downlights you arent utilizing the capability of the control system.
Different lights and lamps can be used in conjunction to design a lighting scheme that combines for example, hidden cove lighting by led strip, table lights with tungsten, spotlights by lv, corridor lights by cfl and so on.
Low voltage lamps can have a habit of failing very quickly. Points to watch for to prevent this is, dont use the cheapy lamps ie packet of 10 for £2.50 use quality rated lamps. Ensure they are well ventilated so they dont overheat, use soft start dimmers on them and underate the circuit.
I would forget about fibre optics unless you want to create a specific effect with the fibres, the light generator is usually HQi and creates a great deal of heat and is expensive.
As far as your questions go, the best kind of light is that which is most appropriate to the task, it could be a candle it could be a 1w led or a 300w flood.
The Clipsal dimmers will work with any kind of lamp that can be dimmed though some fluoros require specialist dimming.
Er low cost high quality, not a term I understand


You can use 35w rather than 50w lv lamps but again ask yourself where you want to have 30% reduction in light. Better to have 50w dimmed by 30% unless you need to reduce the loading on the circuit.
You would benefit from going to a good lighting showroom where you can see the different kinds of lighting on display and controlled and talk through your requirements with them. Dont expect to get lighting design advice from an electrician.
Good luck