Wiring domestic ceiling lights

Background
I want to do some basic wiring of ceiling lights (10 amp) before I bring the electrician in to do the complicated stuff.
I want to create the wiring circuit shown in Fig.1. It contains two light circuits: an existing circuit activated by switch S1 to turn on 3 lights (L1a, L1b and L1c); and a new circuit to be activated by S1 and S2 ie this 2nd circuit won’t be turned on unless the 1st circuit is on.
I’m using either twin (only between S1 and L1a) or twin + earth. Fig.2 shows the wiring colours and patterns. The Light has 4 connectors (Loop, Earth, 1, 2) as does the Switch (Loop, Common, 1, X). On older switches the 4th connector (shown as X) is missing, while on newer switches it has a removable cover.

Questions

1. Are all connectors on the Switch and Light isolated, until bridged by either the switch closing or a light bulb inserted? The reason I ask is because for the new wiring I’m only using twin+earth and would like to use the X connector on the Switch for the earth wires.
2. Is there a convention on the Switch about whether Active goes into Common or 1?
3. Similarly, is there a convention on the Light about whether Active goes into 1 or 2?
4. I'm using the standard bayonet ceiling light fitting - is this what is referred to as a ceiling rose?
5. Figs.3 & 4 below represent my understanding of a basic light circuit, looping either through the ceiling light (Fig.3) or switch (Fig.4). Are they correct, because I don’t understand why connector 1 (in both diagrams) has only 1 wire?
6. And the biggy – is Fig. 1 correct?

The attached PDF document has the images for the following 4 figures:
Fig.1: Two light circuits: one activated by switch S1; the other activated by S1 & S2.
Fig.2: Wiring colours and patterns.
Fig.3: Basic circuit - Looping at ceiling rose
Fig.4: Basic circuit - Looping at switch

Attached Files http://www.renovateforum.com/images/attach/pdf.gif ElecQuestion2.pdf (45.6 KB)


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