(1) I mean actual book chapters.

Answer 1: Oh, haha. In that case... An estimate of 20-25 each.
(2) I'll be 25 or 26 then...

Understandable, though.
...do you think we contributors could get a special preview to help tide us over?

Answer 2: As in.... free merchandise on behalf of 2100? Then of course. It's not a concern to me at all, and you will all see the spoilers eventually anyway (only the contributors are allowed to see it, meaning those who have worked hard on 2100 in general).
(3) Who are the "villains" in this story, and how would you describe them
Answer 3: Currently, we have:
-The Archfiends
-The Drocons/Raptors
-Every one else
The main antagonists are the so-far mentioned Archfiends:
-Yanma: The Archfiend of Gluttony and an insectiod whose goal is to devour powerful prey to become stronger (doesn't need to eat to sustain any part of himself).
-Daen: The creator of the Archfiends and sort of the villain Yanma was based off of. He created Yanma by accident after failing to overpower Karoku's soul during his childhood incident. Daen is kind of the reason the Archfiends won't die no matter what, even if the main characters manage to beat them somehow.
-Kensaku/Shikome: Shikome is the Archfiend of Sloth and she's a demon within a mirror that resides in "Lucifer's Garden" (Daen's haven). Kensaku, as we know, holds the Black Mirror, and he's a Drocon/Raptor as well. Shikome can only be fought within dreams or is otherwise nearly invincible due to the fact she's only existent as a reflection. She aims to harness Kensaku's mirror to become fully invincible. She currently antagonizes a cat-girl named Kinme.
-Kinyou: The Archfiend of Lust, and a demon-vampire-succubus enraged with Karoku (and Kohaku, through a sort of jealousy and sadistic torment). She wants to do a bunch of "things" to him, which of course includes killing (but subconsciously does it while she feels otherwise). She also antagonizes Kohaku because she won't let her tell Karoku her feelings (being only one of their many obstacles that keeps their romance apart from each other).
-The other Archfiends: All prevent their hosts from achieving a goal of some sort, and generally end up giving them a bad reputation.
-Fince Recleoura: Violet's older brother who claims to be the messiah of the Drocons, and wishes to claim Earth on his own (Shikon's less-powerful replacement, and a sort of "first villain")
-Aiones/Saraphalis (new): Aiones is a living computer-virus accidentally created by Dr. Claude, and an experiment stolen by Fince trying to utilize a battle-strategy against Earth's defenses (due to their lack of knowledge). Cybernetic characters such as Madeleine and Shimiru (new) get infected by Aiones and turn "evil" for awhile, hence the "D.E.M.O.N." (DEath-Metal ONslaught) virus. Saraphalis is actually two hyper-cells merged together (single-celled aliens the size of humans), that came from the Drocon's previous planet along with Matra. Saraphalis is an angry life-form bent on getting revenge on the Drocons for destroying their planet. Their goal is to find the perfect vessel to split into two cells (with half of Saraphalis' face replacing his heart), and destroying the quadrant by merging with a "Reactor". Saraphalis is a Drocon villain (but not exactly
a Drocon) as well, just to be clear. His kind of hyper-cells can infect anything, and because of their primitive ancestors of "Safalligens" (human-sized viruses), the Drocons carry that unusual eye-infection that's been killing them off. Saraphalis are true aliens.
-Sine Recleoura (new): Fince and Violet's father, and the main antagonist of 2100. He's part-Drocon and part-Raykaran, and has been living on Earth for as long as only he knows. He's at the boundary between the evolution between Drocons and Raykarans (the opposite), making his kinds part Raykaran in a way... His goal is to bring upon the end of the world and taking the chosen 16 to start over. He sees himself as the God of the universe, and is God in a way (but not the God from our life). The reason he's evil despite caring for the main characters, is his harsh and cruel opinion on the others. He gives everyone else the capital "L", and thinks they should die. Ever feel like maybe just because God thinks you "suck" that you don't deserve to live makes you feel like crap? Well hell, it makes me feel bad, which is why his actions leading to these prophecies, such as Daen and such, makes him the manipulator of all.
BUT.... There is a TRUE antagonist...
If you want details, pm me if you want to read Rodney's final hours...
(4) With the inclusion of Olbap Nandofer and the Elven race, what type of
elves are you featuring? Basically I'm wondering if it's faerie-type, tiny-type, or Tolkien-type.

I ask mainly because a) I absolutely adore Tolkien's elvish race, and b) I'm finding the Farraen race to be a counterpart of sorts.
Answer 3: He's a human-sized one and adding more elves will be fine. Not sure what type of elf to consider him, maybe Tolkien (or something close to what Link himself is).