Starting July 30th, you will no longer be able to log in to a Curse account that was not merged with a Twitch account. If you have not yet merged your Curse account with a Twitch account, please do so here! Otherwise, your account and its content will be inaccessible.
Command blocks and commands are available on x-one with the better together update (although bedrock is limited compared to java). The Switch will get bedrock edition soon as well. Old gen will never get these things.