Sorry, I'm new to the forum so i couldn't have seen this when you posted... so any "advice" I might offer will likely be far too late, but here goes anyway...
First, as far as I know, yes you can lend across any of the nooks, even to Nook for PC. Unlike the Kindles (afaik) you can ADD more memory via SD micro (I have a 32GB card in mine)
What it really boils down to for me, is how do you really feel about reading and what and where do you like to read? If you prefer the feel and look of paper and ink, or reading in natural light, and are going with an ereader for the convenience, I highly recommend the simple touch (or an original nook if you can find it). eInk is the greatest IMO.
But, if you like to read in dim places and just don't want a book light (though the new simple touch is supposed to have that covered to), or really like comics/manga/graphic novels or other media that just wouldn't translate well to black and white... or if you intend on using it for apps, then the only B&N choices are color or tablet.
I'm not up on the exact differences between those two, but it likely has to do with whether you're allowed apps outside of B&N (but there are ways around that)
