Levels run from 1-30; these levels attempt to capture the feel of the "sweet range" of 3E, which is levels 7-14.
Roles such as the "leader", into which the warlord and cleric fall [and, presumably, bard, if that class makes it in], won't require the character to stand around doing nothing but making other people better (through songs, or healing), but rather will gain access to those abilities in addition to actions he or she might want to take. Lead designer
Rob Heinsoo on PC roles.
Design & Development: Class, on fighter weapon choices: "Fighters care about which weapons they use much more than other characters. Other character classes have specific weapons and weapon types that they tend to rely on while still maintaining access to a larger chunk of the weapon chart. The fighter is the only current 4th Edition class with capabilities that depend on the weapon they have chosen to train the most with. Even at 1st level, a fighter who uses an axe has a different power selection than a fighter who relies on a flail or a rapier or a pick. In the long run, fighters can diversify and master powers related to a few different weapons, but most will opt to focus on the weapon that suits their personal style, helps their interactions with the rest of the PCs in the group, and carries all the magical oomph they’ve managed to acquire."
Mentioned that paladins can be of other alignments other than lawful good.
Classes can be improved by racial feats, in a similar way to how current racial substitution levels work.
Peter Schaefer talks about racial traits ("Being really lucky, for example, works with the halfing rogue really well, and being durable is perfect for the dwarven fighter.") and how different classes can perform the same role without looking like clones of each other.
There will be rules akin to the retraining rules in PHBII
Vancian system survives, but it's only a "fraction" of the magic (or magic options) available to characters: "a wizard who casts all his memorized per day spells should be at about 80% of power."
"Wizards will be able to cast 25th-level spells." 4E mechanical designer Logan Bonner also comments very briefly on the rumours of 30th level spells -- "Power level corresponds to the character level at which you gain the power."
Wizards have been seen to use a "wizard strike" (twice in a single combat) and a "once-per-day scorch" which blasted three opponents who were lined up in a row. Neither appear to be spells.
Wizards get a couple of decent ranged area attacks per encounter.
Wizards have a "wizard strike" which injures and pushes foes; warlords have a "tactical acumen" ability which can give bonuses to allies (source).
Monsters no longer drain XP (implied no draining of levels?)
Ancient (red?) dragons apparently now can do a lot of things ((the dragon can't do all those things every round - that was clarified by Wizards' staff in the gleemax forums):
An inferno aura, useable as a free action.
A tail slap attack with an added pushback effect, useable as a free action.
Two claw attacks, useable as a standard action.
A fireball spit that sticks to the target dealing extra damage, useable as a standard action.
A breath weapon, but we don't get to see what kind of action it normally takes - a free one like the inferno aura, as different uses of the same ability?
A special action granting an extra standard action.
They may take an immediate action to use their breath weapon when reduced blow half damage.
They may take an immediate action to use their tail slap when about to be flanked.
Said dragon would have around 1000 hit points.
Action points are core. They do different stuff than Star Wars force points and Eberron action points.
Hit points appear to have level ranges during which certain abilities are accessible -- "For example, you drop below half HP, you become Bloodied. Then there are abilities you can only use while Bloodied, and abilities you can only use against Bloodied opponents. (Sounds like Fighters can get a Last Stand buff, while Rogues can unleash some nasty attacks against Bloodied enemies.)"
On saves vs. massive damage -- "You may have to make a Fort save or suffer penalties for the rest of the day, but you will not die from massive damage unless it drops you to -10."
Full attack option removed -- WotC's Andy Collins posts in this thread (seventh post down) that the full-attack option has been removed from 4th Edition. He also briefly discusses the designers' goals to create more mobile combats. Removing this option reduces the "shall I stand here and fight or move?" choice prevalent in 3E combats; added to that, of course, is the previous info that Attacks of Opportunity (pasted below) have also been either changed or removed, presumably with the same intent -- "we're designing the game to encourage, even mandate movement from one place to another. More powers that reward movement, more short-range teleportation/flight, more powers that involuntarily move enemies...these all get us away from the static fights that 3E encouraged."
Social interactions: Multiple checks between multiple characters (including back and forth) for a single social interaction, instead of a single roll as now. Tools for helping DMs manage a social enounter which has suddenly been thrust upon them without warning; the example given is that the players suddenly decide to speak to the mayor, an event for which the DM is not prepared.
Skill system – familiar but truncated. Getting rid of tailor, rope use, etc. Focus on the skills that are really useful in an encounter. Star Wars Saga Edition is a significant stride forward and should be considered a preview. Same for profession, etc. We want characters making acrobatics, bluff, jump, etc. No characters will be stuck at 10th level saying “oh I never invested in that.” Hide/Move Silent are brought together. Now an important part of your character, and here’s how to apply it to an encounter: "It’s rarely a check and done, it’s now, I make a check, and they react to it. What happens now?" (source).