Just commenting on your glucose blood work
" In April tests, HbA1C = 5.6, Fasting Glucose = 93. Both a little high for my tastes, but don't appear terribly problematic?"
Actually, IMHO I do think those numbers are a problem because of APOE4. For starters, HBA1c going up to 5.7 is cut off to pre-diabetes, so you are almost there. And even though BS of 93 isn't bad compared to the rest of the population, 1/3 of general population is diabetic and up to a third are pre-diabetic so although that may be better than the population in general it is not optimal.
My understanding is bc we have more LDL particles floating around bc of poor clearance they can be oxidized more easily just because they are there longer. Plus see the quote below...APOE4 binds three times more easily to glucose molecules compared to E3's. That means those extra LDL's we have are oxidized even more quickly with higher blood sugars. That can mean LDL depositing in artery walls as plaques and the APOE 4 molecule cannot deliver the fats and cholesterol to the neurons which may be the start of the progression to AD. So it appears that keeping blood sugar levels as low as possible would undo some of the issues of being APOE4.
This does go along with observations of diabetics being more likely to have AD.
"ApoE-4 shows a three-fold greater AGE-binding activity than ApoE-3 explains that when there are more glucose molecules in the blood stream (diabetes and pre-diabetes) APOE4 binds 3 times more easily to glucose than APOE3 which then makes that glycated APOE4 molecule inactive so that even less nutrients get into the brain! So having high blood sugars may be the worst thing we could have happening to progress to AD."
Here is link to that article http://people.csail.mit.edu/seneff/EJIM_PUBLISHED.pdf
Your numbers are pretty much what mine were this past February but I haven't had the guts to find out if my arteries have plaque build up started. By going lower carb my fasting BS is now 70, when it was mid 90's. And my HBa1c was 5.6 -don't know what it is now, but will know next month. So, IMHO, keeping BS low is possibly ONE of the most important things APOE4's can do to ward off both AD and CVD. The hard part is keeping LDLp lowish while doing it. I think that is where Julie and Gilgamesh and others have had great success with calorie restriction. Probably one way exercise helps too, bc that increases insulin sensitivity which keeps BS low.