Here are a few things I would do if it were my project.
-Re-organize all of your files into sub folders, to make it easier to find things. If you do this consistently and follow it on all your projects it will make your life easier down the road when you have to come back to it in a year.
-I would move every power flag so that it is pointing up and every ground so it is pointing down.
-You have some text and some designation that overlap components, I would space stuff out more to alleviate that issue. If you need more space than make the page size bigger or else split it into a hierarchical sheets.
-For the PCB I would double check my manufacturers specifications, put them into ki-cad than re-run the DRC. It looks like you have things that are too close together, and too close the edge.
-The silk screen around the pin headers is hard to read.
-The foot print for J13 look wrong with those holes inside of a pad. There is probably a better way to draw that in ki-cad.
-Don't put vias inside of pads.
-You might find it easier to use your two internal layers for a ground plane and a power plane. Then route signal tracks on top and bottom.