This is a legitimate question, I often wonder what will happen with this product and the fate of our libraries. Customer service has already gone to the dogs, so what will happen if the Nook isn't around anymore?!
Nook may be on shaky ground, but here is why I think you don't need to worry:
If you look at any of the articles last February talking about the poor Q3 2013 numbers, there was mention of less focus on hardware, not of abandoning hardware altogether.
But the media likes sensationalism, so they're going to give you nothing but doom and gloom. What's interesting is that the media is now complaining about the very thing they've been telling B&N to do for the past few years. What do I mean? The Nooks have always received high marks in hardware, it's the one thing on which they all agree. The negatives are always pointed out as being software and content, especially the app store. So, now that B&N says they are going to shift the focus (and they are, in-app purchasing is coming, they say international expansion is still on track, they're still signing deals with movie studios) the same journalists are now shouting that the sky is falling. Even though this is what they suggested B&N get to in the first place.
Once again, B&N (or is it Nook Media?) has some work ahead of it. the tech media have been saying for the last 3 or 4 years That B&N will be dead "next year". But it's not, and it's still chugging along and with a cash balance, you know, the thing Amazon doesn't have but Bezos is somehow allowed to get away with. Sure Wall Street maybe on edge, but the device itself is still popular enough to be mentioned in just about every tablet article (Apple > Google > Amazon > B&N).
My 2 cents... or 3
(also yes, to your other question, you can download the nookbooks directly to your apps on both iOS and Android)
I don't see that anyone answered your question about the wifi access. My understanding is that your device will download the books and you will only need wifi to sync the app with your nook. So you should be able to read on your device without the wifi as long as you have downloaded the book while on wifi.