Although I do rip out the hardware I won't be using just to be extra safe, I don't think physically removing or disabling hardware that requires you to physically plug a cable in to operate is completely necessary, as long as you are pretty sure you won't absent-mindedly hook it up. I would recommend physically removing WiFi adapters and other wireless connectivity hardware, though.

Yeah, I would move away from BitLocker when you get the chance. It is closed source as you point out, but there are also widespread concerns that the FBI encouraged Microsoft to code a backdoor in it for them, as well as it suffering from some pretty major security flaws. My go to open source encryption software is either LUKS or VeraCrypt.