[VetteVet]

My advice to you was fairly generic because of the different varieties of wiring harnesses out there. It is based on what I've learned and my experience.

I see that you have done some of the things that I recommended and mostly what you have left to do is standard circuit wiring for your load items, and how you want to route the power to them. The way you do that is up to your preference and it helps to study how others have done their systems.

The fuse panel is necessary because all the circuits need to be protected to avoid damage of components and fires. It should be obvious as to what circuits and wires will go where in the fuse panel. If the EZ wiring directions do not specify what wires by gauge and color go where, then you should get familiar with the GM suburban harness and learn what they used. I see that the turn signal wiring does not follow the colors GM used, but the wire sizes seem to be correct. You should make a log of the colors you are using just for future reference.
As far as the sizes, i would not use a smaller gauge than recommended but a larger gauge is ok unless it is needed for a specific reason. A good example is the resistance wire for the alternator. The red power wires in the OEM factory circuits are 12 gauge but there is nothing wrong with going larger, especially if a larger alternator and more amp draw loading is in play.