You would need new classes.
I would recommend tweaking some classes, like the warlord. Take out the healing, give him slightly better armor proficiency, and a raft of social utilities. Base his abilities on Charisma, and make it clear Intelligence is not necessary, but a warlord with high Int would be considered more dangerous. Strength would probably not be that important. The warlord would be a noble captain/count or something along those lines. Other nobles would be "knights" instead (possibly using the knight class). I'm not sure what role this PC would have, as it's sort of a mix between controller and soldier (leader). I could picture a paragon path for more intelligent, "lazy" warlords, if one doesn't exist already. (I'm thinking Zhuge Liang, even though he wouldn't fit in a western setting.)
A lot of social roles wouldn't be suitable for PCs. A guildmaster, for instance, is an NPC, and likely a minion. Priests would usually be minions, perhaps with rituals if you're still using "subtle" magic. You don't need (or want) a traveling merchant class. That's a theme that a PC could take (and most NPC merchants would be minions). Bard would also be a theme.
"Take out the healing"... if you're removing magic, you won't have clerics or (magic) bards anyway. You'll need to come up with a different mechanic. One suggestion might be simply more hit points, which degrade over the course of the day/adventure. Another alternative is the Gamma World solution. In GW, origins are basically classes, and are selected randomly. A few, like Mythic and Electrokinetic, are essentially "leaders" and have healing powers, but most don't, and you can (and will, if you play GW) experience parties with no healers. In GW, Second Wind is a minor action and heals 50% of your hit points. Healing powers (like what the Mythic has) are pretty weak; the Mythic can heal 1 hp/level once per encounter. Needless to say, random vampiric mutations become valuable (along with ways to counter them). Between encounters, PCs heal up to full. Gamma World PCs have no healing surges, as the unit of combat is the encounter, not the day/adventure.
IMO, you should still allow full recovery with extended rests. No, it is not realistic, but if you don't do this, you have PCs who won't adventure beyond a day. They'll go back to base, rest up, then wonder why the villains keep winning.
D20 Modern is helpful here. Look up the MSRD if you don't have it. Look up the Surgery feat/rules. (The feat merely takes away the penalty, I don't know where the rules are exactly, but I'll short form them. In addition to quick 1/day healing of a measly number of hp without appropriate talents/classes, you can use surgery. This heals 1d6 hp/level of the target, is effectively a martial practice [ritual] which takes 1d4 hours, and afterward the target is fatigued for a period of time, based on how well the surgeon rolled. You can only perform surgery on a character 1/day.) Use this is you passionately hate having PCs fully heal at the end of the day. Expect daily surgery, and make sure someone takes that martial practice, or, failing that, make doctors easily available. (Realistic healing rules just do not suit adventuring.)
Monsters are easy. Custom-generate generic and unique NPCs. By the ton. They could literally all be human.
