Hm. The Ibanez site definitely says it's an Edge, but in the photo, it looks like a Lo-Pro, which the S1520 has.
I think there are very few (if any) high-end bolt-on Ibanez models that don't use AANJ... the JS
series is the only notable exception i can think of at this time. The S series are definitely AANJ.
Rest assured that even though it has limited face inlays, it will have a full set of side dots.
I don't think a natural or oiled finish will make a guitar lose
(not "loose") sustain. I've heard that compared to a hard clear finish, oil finishes can be a tiny bit less bright, but other players swear by natural finishes, saying that they "breathe" more. I think it's all anecdotal and subjective, so choose what works for you.