A building would have an AC, although it would be fairly low. (A city wall was described as having AC 3 in the online d20 SRD.) More importantly, the walls of the building can be described as having a certain number of hit points and a level of hardness dependent on the materials used to construct it. When figuring the damage from an attack, reduce it by the material's hardness and apply the rest to the hit points of the structure's wall. When the wall's hit points are reduced to zero, it's destroyed.
Advanced combat is a somewhat disingenuous name, as it implies that these rules are more complex than the "basic" rules found in the PHB. In truth, some of them are and some are not. Mostly, we look at these rules as a revision of the existing rules to make them more useful to players and DMs. In part that means taking incomprehensible portions of the combat system (grapple, for example), and cutting them down into discrete actions people can actually use without a half-hour argument. Partly this means taking basic combat actions and making sure that they have a valid purpose at all levels of play.
Grapple is collectively 3 separate maneuvers that all fall under the super-heading of "grappling". Any grapple attempt provokes an attack of opportunity unless your attack has the edge.
These three manoeuvres are: grab on, Hold down, and lift. When combined with the Tome of Battle manoeuvres that provide for some fairly judo/akido like moves, you should have a fairly straightforward martial arts system. You may also want to look at the Tome of Tactics (homebrew) or the Cthonic Serpent homebrew school or 8 more lesser disciplines. They all offer "grapple" mechanics or powers that should, if synergized, offer an appropriate milieu for your wrestler.