[Nil Einne]

I don't think this means it's sold out for good, I suspect more will be coming. It's just sold out/out of stock for now waiting for more stock to come. (They probably also need to reserve some of the current production for retail partners including outside the US, Canada, various places in EU where it launched.) It probably doesn't help that Kobo doesn't seem to have a good way of indicating estimated delivery date or keeping people up to date with their orders so most likely don't want to take orders too far in advance. (And even Google who had a slightly better system in place stopped taking orders for the Nexus 4 when the pre-order time was about 8 weeks.)

As for numbers, it's hard to say. From what I've seen Espresso seems to be the most popular, perhaps because it's somewhat unique yet isn't so bad as to be unappealing so that may be one of the reasons it sold out first.

In any case, I don't think the number of screens is really known, the 300k number seemed to came from the same source that said they were going to be for the Nook/B&N, which seems to be incorrect so I'm not sure how reliable that is, and there's no indication (or really any reason) to think eInk isn't still producing them. While Kobo have branded the reader as limited edition, it's not really clear what this means, if anything beyond marketing and the fact that it's an expensive device so they don't expect it to be their mainstream model and aren't sure of how well it will sell. (There is speculation it could be replaced in September-October but who knows?)