Moisture loss is about evaporation, so quitters/clears will have it at the same rate until near the end of incubation. Tho the air cell in a quitter will degrade and be noticeably harder to trace than a live egg, that shouldn't effect things either way.
35-40 should be pretty good, unless you live at altitude(in which case I don't know exactly what you need, only that hatching can be very challenging). I feel that running a bit dry is safer that running a bit wet, but also that there's no need to fuss too much. If you have a bad hatch and you have a lot of chicks pipped internally and then dying, that's the time to change. Right now what you're doing could be perfect, and if you mess with it you won't know.
I candle obsessively and like to mark air cells but I find them unreliable, i judge my humidity by weight too.