Mechanical advantage is really pretty simple, but if you've never thought about it, it might be confusing. Just remember what some old dead guy said, with a long enough lever, you can move the world.
If you want to use V-brakes then you need levers designed for V-brakes or a little gizmo called the "travel agent". I have a bike with a front V-brake and Campy break levers (designed for caliper brakes). To make that combo work, I've got a travel agent mounted to the V-brake and it works perfectly. Google for the travel agent and you'll find a bunch of info. Some are for sale through Amazon (where America shops).