The side chamber is usually 60°-100°+ degrees lower temp than the main chamber so it would be hard to make jerky in both parts of it. You could make jerky in that side chamber, but you would have to crank up the grill to a temp that gets your side chamber to somewhere in the 140°-180° range. You could also use the side chamber for hanging sausage, meat sticks, etc. There are 3 channels in the top to slide hooks to hang or buy other hooks and put their hanger portion in the channel or hang off of the three hooks provided. If you can afford it, go ahead and get it. It also works as a great warming box to keep food warm if you are still cooking something in the main chamber.
The shelf is especially nice to have if you have the side chamber. If you don't have the side chamber. I don't think you necessarily need the front shelf because in effect you have two side shelves to place food on while loading or unloading the grill.