If you have experience with soldering then you should technically be able to replace, or simply re-solder the ports to regain functionality. Are you having any other issues with the computer besides those? If the damage has gone further into the board than the base of the USB ports then you may need to look into replacing the logic board entirely to really regain the functions.
As far as your other question, there isn't a hub for ethernet or mini display as far as I'm aware. There is for newer computer that have the thunderbolt instead of mini display, but not much more than that unfortunately.