re: Cake from scratch.

I use AP in cakes, as I don't like (bleached) cake flour (though it's getting easier to find King Arthur's unbleached cake flour). Definitely don't pack the flour. You don't have to sift before measuring, you can stir the flour to aerate before spooning into a measuring cup. DON'T stick the cup into the bag and smash the flour into it. This will give you 1/2 to 1 1/2 more ounces of flour per cup...definitely enough to make your cake heavy.

If it tasted floury, the flour was not cooked sufficiently. Was it an oil cake (chiffon type), or a butter cake?

I bake with almond flour/meal all the time; it is not a 1:1 substitution with wheat flour, and it will not yield identical textural results. Best to use a recipe formulated for almond flour if you choose to use it. The easiest cake I know calls for almond flour: Dorie Greenspan's french yogurt cake: LINK
It stirs together in one bowl, uses AP flour + almond flour, veg oil (I use olive), and greek yogurt. A kid could mix it up, no sweat. Plus, it is damn delicious.