For all things, LP should just be considered a newer version of OP.
You may not have to update the BL, but it doesn't hurt. Just be aware that you will have to re-install the firmware after updating the bootloader since BL update wipes out firmware for technical reasons. Follow wiki instructions. It is basically impossible to permanently damage a board without a hammer (or big static electricity spark in the wrong place, or plugging in too much power). The worst thing you can do is install the wrong bootloader, and even then you can use an FTDI and cable to flash it using the System Boot Loader. All other user errors can be fixed with the GCS in one way or another.