The Windows install you have will be an OEM product key which Microsoft won't activate online. Sometimes you can call them and they might give you a new product key so it will activate. Don't tell them exactly what happened though. You are only allowed to change 2-3 components of a computer before they class it as a different computer.
Alternatively, download Windows Loader by Daz (Google that exact term). It will re-arm the OS with some clever trickery and as the product key isn't blacklisted, it will always show as a valid copy of Windows.
As for the mouse, try deleting the pair from Bluetooth settings and pairing it up again. If that fails, reinstall the bootcamp drivers (some Mac's come with slightly different BT chips and require a different driver).