in response to the OP;
1) yes twin wiring is better for sure but note that each lamp may have its own ground return path anyway, so you need to be careful about keeping all the lights and the generator wired up in the same way.
2) No overvoltage protection is required; it is built in to most modern LED front lights. Rear lights vary; all will be OK provided the front light is connected and working, but some will survive as the only light connected to the generator and others won't; read the small print.
3) I don't know how many miles you plan to ride on this bike but if it is more than a few then I'd vote for fitting a hub dynamo even if it means you end up with much cheaper lights; even fairly cheap LED lights are pretty good these days.
Even if you think you only might get a hub dynamo later, and will use a bottle generator for now, I'd vote for getting a front light that is meant for use with a hub dynamo, i.e. with a switch in it; it will only cost pennies more.
Provided you have some half-decent reflectors at the front and don't plan to stop in the middle of the road, I think the value of a standlight at the front is somewhat limited.
cheers