This looks like it may work, a few questions though.
1. Why use the red wire then change to black? isn't the white one normally used then marked with black tape.
2. Where the 2 wire branches off the feed for the light, it looks like this is spliced in, can this be done? I would be able to do this in the 3 switch box, this would solve my problem. I am trying to avoid running a 2 wire from one light to the next due to ,locations and insulation etc...
You can use the red wire or black wire for the returning switched power, not the white. The white can only be marked and used as a supply conductor. As defined in 200.7(C)(2)
200.7(C)(2)
Where a cable assembly contains an insulated conductor for single pole, 3-way or 4-way switch loops and the conductor with white or gray insulation or a marking of three continuous white stripes
is used for the supply to the switch but not as a return conductor from the switch to the switched outlet. **Or light** In these applications, the conductor with white or gray insulation or with three continuous white stripes shall be permanently re identified to indicate its use by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.
You can splice two wires from the switch box, but you need to watch box fill.
What type of lights are these? cans can usually accept two romexes.