Look into this, as a USB power switch: Locate F1 on the board, remove that, mount it on a switch that you then hotglue to the board, maybe on the bottom, or to the female headers, then make the connections back to the board.
For replacing the socket - I would browse someplace like herehttp://www.cypressindustries.com/products/usb.html
find the connector you want. Put some leads on a part, wire the leads to the holes in the arduino board, then epoxy down a piece of insulating material and mount the connector to the top of that, finishing up with ground wires to the 2 large holes.
Or save yourself a lot of hassle and get a seedstudio arduino http://www.seeedstudio.com/depot/seeeduino-v22-atmega-328p-p-669.html