Ok here is how it happens, take T3 at LHR as an example, your baggage is bar coded before it is sent down to the spur, on its journey the bar code is scanned and a buffer rather like a large boxing glove "punches" it down the correct tunnel thus down to the handlers who are working your particular airline. british midland handles Virgin. Alitalia, Iberia, SAS and aerlingus handles air India, Cathay, Thai, For Example. On long haul flights the bags are packed in tins (containers) a 747 takes 7 usually one upper class one premium and five economy. These are already on tugs and bags are loaded according to the class your travelling in. A part of the sticker on your bag is taken off as its loaded into the tin and placed on a clip board in the order in which it came down to the spur, this tells staff which tin your bag is in so it can be off loaded if your asked to leave the aircraft or you dont make it from the duty free shop before they close the gate. If you request a "fragile sticker " a handler will come up to check in 30 mins before the flight is due to depart to pick these items up. I assure you we have no seperate hold for these items, they are either packed at the top of the last tin on the train, or loaded onto a flatbed truck with the mail and crew baggage and then loaded into the tail section, Push chairs wheel chairs and the like (unless your travelling upper class ) are also loaded here, some netting is hooked over the "pile" so it doesnt shift to much. all items here are still "chucked "on and off a belt to and from the hold and indeed "chucked "off the truck onto the belts for your collection. If it looks like you really do have a few quids worth, an agent will pick it up off the belt Airside, and you will collect it from the agent. Hunting rifles, fishing rods etc are also stored here, but they(the Guns) are taken and examined by customs long before you get them back.
The claims for "fragile" items broken every year are staggering BUT they only pay about 20%,(which is loaded into your ticket) So as I said take it into the cabin with you.