I've read through all three
FW HH books and have been following news about the later books as closely as someone on the wrong side of the Atlantic could, so I'll see what I can do to help.
Book 2: Iron Hands (Ferrus Manus), Salamanders (Vulkan), Night Lords and Word Bearers (Lorgar). So, no Conrad Kurze model yet, and Vulkan is the last released one--this summer.
Curze has been announced as the next model. They're trying to finish up all of the Book 2 stuff before moving on to Book 3. At least as much as possible.
Book 3: Alpha Legion, Imperial Fists, Raven Guard, and Iron Warriors. None of these have Primarch Models yet (and I have not bought or read this book yet so I actually don't know anything about the information in here).
There's certainly a ton of wonderful information in it. The Imperial Fists and Alpha Legion background are my favorite parts, but all four are fantastic. Not to mention all the information concerning the Taghmata Omnissiah, which represents the local armies of Forgeworlds (separate from Titans, Skitarri, or Ordinatus) that are called upon to add their numbers to the Mechanicum's armies. Basically it's the equivalent of "Calling for the Bannermen" to use a feudal phrase.
So...in total we have 8 of the 9 "Traitor Legions" with background fluff and rules and specialist units, with 5 of them having Primarch models. Only the Thousand Sons are omitted thus far. On the Loyalist front, we have only 4 Legions described, and only 2 of those have models. So, what do you think? If you play one of these armies (either in HH or 40k) what do you like? What got nerfed, or didn't live up to your expectations, and what was perhaps a cool surprise, that enhanced your love of your chosen Legion or Chapter?
It's important to keep in mind that the legions were massive and any of them could have a mix of traitor, loyalist, and other elements as part of them. So even though only the majority of the "traitor" legions have been given rules, there is lore to back up having a loyalist element of any one of them fighting against a traitor element of any other.
Secondly, do you have any thoughts about which other Primarchs might get rules and expanded biographical information in the (future release date still to be determined) fourth Horus Heresy book? The Isstvaan trilogy has now ended, and I know they will be dealing with the hunt for Corax on Isstvaan V, the space battle between the Imperial Fists & Iron Warriors where Perturabo is almost destroyed, and then Alpha Legion vs. Mechanicum (is this a real event that I have not read a book about? I'm not familiar with this third one).
The fourth book actually details a series of other smaller campaigns that were happening across the galaxy and includes an Imperial Army list. The hunt for Corax on Istvaan V is detailed in book three, as is the Battle of Phall and The Invasion of Paramar. Paramar is a new battle that was meant as a means for the Alpha Legion to prove their loyalty to Horus, who even after Istvaan V, was not sure of his shadowy brother. However, it also involves a loyalist Iron Warriors detachment who happened to have arrived on Paramar as part of a normal repair and refueling operation, and weren't yet aware of their legion's loyalty. So the real battle is Iron Warriors, Taghmata Paramar, and the Legio Gryphonicus, vs Alpha Legion, Taghmata Satarael, and the Legio Fureans.
So, we don't have Primarch models for Perturabo or Dorn yet, (though there are rules in the 3rd book which I haven't read yet--please tell me what you think) nor do we have background rules or a model for Alpharius/Omegon, and those would all be awesome to get and sound like they would fit in this 4th book.
Alpharius and the Alpha Legion are covered in Book 3. There's even a great list of origin stories regarding his homeworld and his discovery. All of which are stated to be false.
(On another note, does anyone else think all the Primarch faces look really wrinkly and old? What's up with those foreheads? They look like 60 year-old men who have spent too much time in the sun)
A combination of
FW's not so great paint jobs and Edgar Skomorowski, one of the two primarch modelers, having a tendency to make them look older. The only primarchs I'd agree with you on are Lorgar and Mortarion, which happened to be the only two primarchs Edgar was responsible for. Most notably, he has been moved off primarchs, meaning Simon Egan, who was responsible for all the other primarchs, shall be doing the remainder of them.
Maybe when a book about Calth and the Shadow War comes out (it's clear this won't happen in this 4th book) they might cover Guilliman and perhaps work in the Lion and Sanguinius from "Unremembered Empire?" I would assume that there would be a "Prospero Burns" book--with Magnus and Russ, and perhaps also Adeptus Custodes and "Null Maidens?" Any other thoughts about themed books and releases?
Calth has been announced as being the 5th book and will feature more Imperial Army, daemons, Word Bearers, and Ultramarines. Prospero has been pushed back (quite possibly to book 7, pushing up the Battle of Signus, but it may still be book 6) due to the complexity involved in both the rules and models of the Thousand Sons, Space Wolves, Adeptus Custodes, and Sisters of Silence, all four of which have been confirmed for Prospero.