What I still don't understand, and it's more the concept of shooting "manual".
Manual meaning you choose the "power" that the strobe will use rather than the camera choosing. Note that the "power" is simply the duration of the strobe is on. On "full power" it might be on for 1/1000s, but at the lowest setting it might only light for 1/10,000s.
If by manual you mean optical/optical my strobe is always going to have to wait my flash to recycle so it can shoot right?
That would only be if you use the strobe on full power. That's why James asked if the strobe you were thinking about had multiple manual settings. The shorter the duration of the flash, the faster it recycles and in some cases it is so fast you can shoot again immediately.
Since I am getting a strobe so I can lighten things better and don't suffer from backstering, why would I want my built-in flash shooting together with the strobe?
If you can't have an electrical connection between the camera and the external strobe, you need some way to tell the external strobe when to fire. You use the internal strobe on the camera to do that. It tells the external one to fire via an optical cable.