[RPG] Thus spake the Warforged: How do their mouths work

Honestly, Don't Change Much

Warforged are widely considered the second or first strongest LA 0 race in 3.5, fighting with Humans (valiantly) for the top spot. If Humans didn't get much of a boost, 'Forged don't need to either. At most, I'd say to alter them for a net 0 if and only if humans got an ability score bonus. However, you may need to alter the text on the Living Construct subtype to make it compliant with any alterations in terminology that Pathfinder made - changes that are subtle enough to be difficult to reference off of the top of my head.

The only other thing to keep in mind is the idea of Favored Class bonuses, but I think that might be a little outside the scope of this question.

Quicksand is a serious threat to a lone warforged who can't make Swim checks.

However, qucksand (DMG 88) initially isn't much of a threat to anyone:

Patches of quicksand present a deceptively solid appearance (appearing as undergrowth or open land) that may trap careless characters. A character approaching a patch of quicksand at a normal pace is entitled to a DC 8 Survival check to spot the danger before stepping in, but charging or running characters don’t have a chance to detect a hidden bog before blundering in. A typical patch of quicksand is 20 feet in diameter; the momentum of a charging or running character carries him or her 1d2×5 feet into the quicksand. [n.b. There is no mention of the typical depth of a quicksand patch.]

So if the warforged is traveling at a normal pace and has at least a half decent Wisdom score, he'll know the quicksand is present and go around it.¹ But it's possible, for example, he charges the Valenar horseman who killed his adopted child and plops right in the middle of a big ol' patch of quicksand. That makes things... challenging.

Characters in quicksand must make a DC 10 Swim check every round to simply tread water in place, or a DC 15 Swim check to move 5 feet in whatever direction is desired. If a trapped character fails this check by 5 or more, he sinks below the surface and begins to drown whenever he can no longer hold his breath (see the Swim skill description).

Characters below the surface of a bog may swim back to the surface with a successful Swim check (DC 15, +1 per consecutive round of being under the surface).

Once in quicksand, a creature must make Swim skill checks to move. And, once a creature sinks, before the creature can move, the creature must make Swim skill checks to reach the surface. There's simply no option to walk across the bottom. Everyone--undead, oozes, constructs--must make Swim skill checks in quicksand. The DM can house rule this away, of course, but, technically, that potentially brutal Swim skill check (DC 15 +1 per round below the surface) can make it impossible for the warforged who sinks to escape the quicksand without outside assistance. (A most amusing "death" for the Lord of Blades.)

Pulling out a character trapped in quicksand can be difficult. A rescuer needs a branch, spear haft, rope, or similar tool that enables him to reach the victim with one end of it. Then he must make a DC 15 Strength check to successfully pull the victim, and the victim must make a DC 10 Strength check to hold onto the branch, pole, or rope. If the victim fails to hold on, he must make a DC 15 Swim check immediately to stay above the surface. If both checks succeed, the victim is pulled 5 feet closer to safety. [n.b. This totally ignores the victim's and rescuer's weights, but whatever.]

Obviously, Dungeons and Dragons 3.5 has fantasy quicksand not the real thing.

1. If using the Rules Compendium detecting quicksand requires a Survival skill check (DC 15) instead of the DMG's listed Survival skill check (DC 8). The Rules Compendium presents this information without commentary.