I used silver duct tape to cover the exposed end of the card. The color of the tape does match the majority of the casing. Of course, another choice of color is dark gray that matches the other part of the casing.
Custom ROM is OS with custom options. Thanks to cmonex, you now can flash the original ROM with her custom ROM or your own. You do not need to swap the ROM's. You just need to flash the ROM with what you like.