I too am solo peds.
5--I keep vision and hearing testing results in "Tracked Data" on the summary page. it's a little awkward: L20/25,R20/40,B20/25 is what I type for a vision test, and 'better than 25dB throughout' for hearing screen. I also keep UA dip results, baby bilirubin tests, hemoglobin results there. I also keep in-office strep test results there.
6--I put LMP there if I want to keep track of it.
2--The rest of the world measures height in cm. I don't know why AC toggles from inches to m. And it is vexing for me and many others that weight toggles from pounds to kg, but without enough significant figures to follow baby weight in grams and they have had repeated requests for pounds and ounces, since this is the way we follow newborn weight.
3--I don't know about the integration of WHO data into the growth charts. This is recommended by the AAP, and at some point it will not be considered good medical practice to use the CDC data currently in AC.
4--I integrate Dev Testing into the notes.
5--immunizations are an ongoing frustration for me. Apparently, I am unable to edit the descriptions they have noted, nor the schedules they have loaded. So, after upgrading to version 6, for example, my PCV13's are coming up as "7-valent" The MCV issue I have worked around, by inventing my own immunization (the program does allow you to do this) called 'meningitis,' and then putting in the correct age range and interval as most recently published.