To simulate the 'skittering along the walls' notion, I had a kobold lair in an old drow temple, with net like 'webbing' woven all along the walls and ceilings. The kobolds, all skilled in Climb, scuttled along the webbing out of reach and flung various weapons and missiles at the party, with the lowest-ranking warriors being forced to fight on the ground, or even trying to up their status by swinging down and trying for 'swing-by attacks' on their woven ropes. (Those that survive ground combat and / or their attempts at playing Errol Flynn may indeed gain in status, and get to hang out near the ceiling, where it's much safer, next time!)
As they are trained to skitter along the walls and ceiling on their rope network, they can trap the ground with no great effect on their own movements. The simplest 'trap' would be a layer of mucky water that conceals caltrops and / or snares. A snare that drags the victim down into the water and holds him there would be particularly vicious!
Having Darkvision, Kobolds should try their darnedest to keep the party in darkness, striking to sunder / disarm any magical light sources, and flinging globes of black clinging mud at torches or lanterns. The only light would come from the occasional alchemical fire attack, and quickly sputter out, leaving the party trapped in darkness.
Using the WotC website's suggestings for beefing up Kobolds, they could have a 'slight build' feature that allows them to squeeze through special tunnels as if they were size Tiny, so that even Gnomes and Halflings would have trouble following them through their access tunnels. Even without that suggestion, a Kobold Adept with a few ranks of Craft (alchemy) might have developed an alchemically-potent 'grease' that the Kobold skirmishers can use to lube up and temporarily squeeze through Tiny spaces...
Craft (alchemy) could also provide some weak variation on the firewine used by Realms Rashemi berskerkers that allows non-Barbarians to go into a limited form of Rage (only +2 Str and Con?) for a few rounds, and the 'groundpounders' might be given doses of this to make them a bit more dangerous.
One of Kobolds big advantages is their human-level intelligence. Anything we can think of, they can think of.