I'll have to bounce your second question about ADE to someone else, as I'm not really well-schooled on that matter, but I can answer your first. A few months after receiving my nook, I began to notice cracks on the right page turn button. This was due to an issue with the first batch of nooks (or so I was told). B&N sent me a new nook with the improved design at no charge; I sent them my broken nook as soon as I received my new one. This whole process took two days. Since I received my new nook, I haven't had any problems with it, hardware or otherwise.
Really though, I'm not sure how much feedback anyone can really give you about the reliability of the hardware. After all, the nook hasn't even been out a full year. But, as I said, I haven't had any problems with my replacement nook so far and I don't foresee any (unless I drop it on concrete or something).