As Blizzard did with the male Demon Hunter earlier this year, they seem to be farming out the new Followers information via interviews. Here are the key bits of info, culled from all of the interviews.
All of the Followers have their own unique personalities and stories. Players will learn more about them over the course of the game and find sub-quests to help their followers and learn more about them.
Lyndon, the Scoundrel. From Kingsport, a “thief in mind and heart” who has some of the best comic lines. He uses ranged attacks with bows and crossbows.
Kormac the Templar is is powerful melee brawler. He’s a tank and is on a mission to recover holy scrolls that were stolen by Archbishop Lazarus.
Eirena the Enchantress has a past shrouded in mystery. She follows a figure called The Prophet and has excellent crowd control spells.
-Followers are only for the Single Player game. They can not be used in mulitplayer. (Presumably this means only for SP characters; you can’t use one if you’re the only character in your MP game on B.net.)
-Followers have all their own unique animations and gear looks. They also have full voice recordings and numerous lines of dialogue to go along with their stories.
-They are available all throughout the game. You can switch between them at will. A new follower will be appropriate to your level when you first hire them; you don’t have to go back to normal to level up a new one if you hire them in Hell.
-Followers do not die; if they run out of hit points they just fall down unconscious for a while, and any bonuses they were granting you vanish for the duration of their nap.
-Followers can not be manually healed with potions, but they will share in your health globe consumption, just like other players or pets.
-They are smarter than the Mercs were in D2, but they’re not going to be mistaken for a human player.
-You can not assign them commands or “ready” stances, though Leonard says you control them by assigning them their skills. Possibly they behave differently, appropriate to the skill?
-They can not use skill runes.
-They can be respeced at any time, for a gold price.
-Followers equip left and right weapons (can use shields), along with 2 rings and an amulet. No other equipment can be equipped, however they each have a special item type; Leonard said the Paladin Templar gets a special tome of some kind. These special items will add buffs or bonuses to the followers and possibly to you as well.
-All of the followers have skills that grant them Gold Find or Magic Find, and they can presumably benefit from MF or GF on their equipment as well.
Leonard was not sure if their equipment would lose durability from use, but I’d guess not, ala D2’s convenience on that front.