A. At least now you understand how important that recovery key is . Hope it was kept safe.
Before you make any changes to your BCD or volume configuration, always make sure you have a handy copy of your recovery key, which can be regenerated using the BitLocker Drive Encryption Control Panel applet under Manage BitLocker then Save or print recovery key again.
To stop having to use the recovery key at each reboot, you just need to suspend BitLocker then resume it. Launch the BitLocker Drive Encryption Control Panel applet, click Suspend Protection, then click Resume Protection. You'll no longer be prompted for the recovery key. You can try performing the suspend and resume before rebooting, immediately after making your BCD changes. Doing so should remove the need for the recovery key for BCD changes, but not for volume changes.
You can also suspend and resume from the command line with the commands
manage-bde -pause <drive>:manage-bde -resume <drive>: