How can i quickly create a cable that i can edit easily to position it, deform it and add gravity?
Use a curve, add one by doing Shift + A then Curve > Bezier. Place and orient the controll points of your cable, to deform it and add gravity select both points and press W > Subdivide. From V menu set the intermediate cuts to Automatic to keep a smooth curve, then position it. If you add multiple cuts spread them to get some space to keep a smooth line.
To make that curve have some volume set the Fill mode to Full. In the Geometry rollout under the "Bevel" adjust the Depth for the width of the cable and the resolution for the amount of sides.