I'm planning on running nylon (or is there any other better plastic fuel pipe?) between my tank and pump, then from the pump to carbs. between each join, ie between the tank and pipe, then between the pipe and pump etc, i'll use braided rubber hose.

does the nylon pipe need any fittings on the end before the rubber hose? like any sort of barb? or does the rubber just push over the nylon pipe, then clamp down with a fuel pipe clip?

You will need some off the barbed nylon joiners or when you tighten the clamps the pipe will just collapse.
You will also need a spec sheet for the nylon pipe from the supplier for IVA.
Robin Hoods have used nylon for many years, works well but the IVA documentation has been a known problem for many years.

You'll need documentation for the nylon and the braided rubber or the correct marking has to be on the pipe/hose.

It's easier to use a solid line for the long runs with flexible ends and, as said, nylon lines can be confusing regarding certification.

Note - be sure to use the proper fuel clips when connecting flexible to solid.

so do you get metal strengtheners that go in the pipe before clamping down on it? anyone got any photos?

CBS do metal and nylon joiners