So, along with everything that was in Kingmaker, the new confirmed classes are…
Oracle: Spontaneous Divine Spellcaster, I.e. the Sorcerer to the Cleric’s Wizard. Cha-based casting. Main features beyond spells are their Curse, a debilitation that comes with bonuses as the Oracle increases in level (for example, oracles woth the clouded vision curse can’t see beyond 30 feet, but have Darkvision for that range, and eventually get Darkvision up to 60 feet, Blindsense up to 30 and Blindsight up to 15), and Mystery, which is essentially their bloodline if we continue the Sorcerer comparison, each with a list of bonus spells and extra abilities (called Revelations) to earn.
Witch: Arcane Spellcaster with own spell list. Int based casting. Familiar mandatory for base class and most archetypes. Main unique feature are Hexes, most of which are spells that are normally limited by per-target rather than per-day (or to be more specific, per-target-per-day, but that will only come up with beneficial hexes) Witches also have a Patron, which adds additional spells to their list, but normally does not do anything else (emphasis on “normally,” as there are rules for special patrons that do add extra features or restrictions.)
Cavalier: Melee class, usually Strength based. Specializes in mounted combat (which has been added to Wrath in a stretch goal) but still has some tricks usable on foot. Challenges opponents for a damage boost, earns teamwork feats that they can grant to allies for a time, carries a banner they can buff everyone with, and joins an Order that augments their Challenge and grants additional abilities.
Arcanist: Wizard-Sorc hybrid: prepares spells like the former, but can cast any combination of the spells they know per level like the later. Also has an Arcane Resevoir they can use to boost spells, or for a second set of powers called Exploits, and can “consume” normal spell casts to restore their pool. Their traditional spellcasting is INT based, but Arcane Exploits are CHA based.
Bloodrager: Barbarian meets Sorcerer. Trades Rage powers for a bloodline and some CHA based spontaneous arcane casting. Bloodrager bloodlines are more ability-focused than their Sorc counterparts, but you can only level in both classes if you use the same bloodline for both.
Warpriest: Fighter meets Cleric, with a dash of Paladin for good measure. Cleric spells up to the 6th level with WIS-based casting. Bonus feats and counts as fighter levels, but at every 3rd level starting at 3. Highlights include being able to trade out a weapon’s damage die for one based on their level, and to buff their armor with extra enchantment bonuses that can be converted to energy and spell resistance.
Shaman: Witch meets Oracle. Wis-based divine spellcaster with unique spell list, plus hexes (some unique to them, some they share with Witch.) Bonds with Spirits, one at level 1 they keep and a second at level 4 they can trade out at will. Spirits grant spells and abilities (ala Oracle mysteries) and grant a list of hexes to choose from. Also has mandatory familiar, like the witch, called a spirit animal that is also buffed by the Shaman’s Spirits.
Skald: Barbarian meets Bard. Instead of confidence, Skalds inspire rages with their primary song, complete with Rage Powers.
Hunter: Technically not yet guaranteed as it wasn’t unlocked before the kickstarter ended, but could still be unlocked in the slacker backer period (and the funds needed are much less than what Kingmaker got from its slacker backers, so odds are good) Ranger meets Druid. All about the animal companion, gaining teamwork feats that they share, as well as animal aspects both the hunter and companion can use to buff themselves. Spontaneous WIS-based casting of Druid and Ranger spells up to 6th level.
New prestige classes and archetypes are not as well known, however. I believe Hellknights (Law-obsessed warriors that can Smite Chaos like a paladin smites evil) and Hellknight Signifiers (Law-obsessed spellcasters) have been all but confirmed, which also gives very high odds of the Armager Fighter archetype (Hellknight in training) being in as well. One of the social stretch goals was for the Winter Witch prestige class, which in TT has the Witch archetype of the same name as a prerequisite (IIRC the prestige class is to the archetype what Dragon Disciple is to Dragon bloodline Sorcerer, buffing up the deadly ice magic aspect of a traditional Winter Witch at the cost of some spellcasting levels.) Several other archetypes and prestige classes have been mentioned by the devs between updates and interviews, but I don’t know what the complete list is.
They have comfirmed that both Real time with Pause and Turn based modes will be available, using much of the turn-based mod that was made for Kingmaker (with the modder’s approval)
Wrath of the Righteous is about the battle at the Worldwound, a place where Demons can enter the world from the Abyss without any limitations. The first (and IIRC one of the only) Mythic adventures, things get really crazy, with the canon ending for 2nd edition Pathfinder causing some serious shakeups well beyond just ending the greatest threat to the world (anything more specific would be spoilers.) However, the TT version was very big on Good kicking Evil’s ass and the power of redemption, and while a path for that kind of story will probably still be in there, Owlcat is talking up the potential of changing the themes to more “He Who Fights Monsters” and “The Road to Hell is paved with Good Intentions” depending on your choices and alignment.