The switch can be replaced with a similar one, just solder it in using a 0.5mm tip and some o.5mm flux cored solder. Fiddly but doable. the switch probably can be obtained from an online supplier or from eBay, you just need one that fits the layout.
The holes are vias to connect through the board or to connect to inner layers of the board, they are often used for testing of the bare pcb, but are actually part of the design to be used as connections.