Well, to take the Beretta 92 apart (Martin Riggs' gun in LW4): push in disassembly button on right-side of frame and, while holding button in, push disassembly lever down on left side of frame (opposite said button), then pull slide, barrel, recoil spring, and guiderod forward off of frame. If you can manage that with one hand or two, it'll come apart.
Most other popular service pistols, although a little more complicated than that, still come apart easily, though it's certainly a two-handed affair because slide disassembly notches, barrel link pins, barrel plungers, bushings, ejectors, sear disconnectors, disassembly levers and so forth have to be pushed, rotated, lined up, or otherwise doodled with in some concert to make them work.
That said, what you have in mind can be done, and pretty quickly, too, but in the midst of a fight, it would be easier to simply throw the gun as far away as possible, or, if you want to take a little longer, dump the ammo one way, the gun another. If you want to know how to disassemble a given firearm, just Google "[type of gun] field strip". As to parts and names, Brownells.com hosts a buncha exploded parts diagrams for a variety of firearms. Just click a part # and it'll tell you what that thing is. The start page for diagrams is here:
http://www.brownells.com/aspx/NS/schematics/SchemMFG.aspx