The new Discovery Sport is the replacement for the LR2, which is no longer in production (though you may see some left overs on the lot and as loaner cars - yuck). From what I heard, the Discovery (replacement for the LR4) will be the biggest, then you have the Discovery Sport, and then there are plans for a Discovery "insert something here" which is even smaller than the Discovery Sport. It will be comparable to the Range Rover Evoque in that line up. I have no idea about the details of that part of the Discovery family.
I wish we had more information on the Defender, but the only thing I know is that there will be a 2-door (probably called a 90), 4-door (probably a 110), and then something else likely a 4-door with truck or something (maybe a 130).
I don't really have much of an inside scoop, just know a lot of dealership people and a couple guys who were at a recent meeting in Solihull. It may be all lies, but seems to be coming true with what we are hearing about the upcoming Defender.