Titanium is one of the lightest materials available, and it never rusts, but you pay for those things. Attached to the frame and is the direct means by which the front wheel is held on. Like frames, forks can be made out of steel, aluminum, and carbon fiber. Steel and aluminum forks are the cheapest. These bikes are not your basic 10 speeds.
Gears refer to the chainrings on the front and the back.
The higher the front chainring and the lower the back chainring, the harder the gear. These are what actually makes the bike go. Major brands of components are Campy and Shimano. This is an Italian made groupo and appears on a lot of profession bikes. For our purposes you don't need to know much about Campy, mainly because very few entry level bikes use this groupo.