Oh man. This all sounds really complicated but it's not. You can sign into Damus and Primal with the same NSEC. You just need to copy and paste the NSEC (Nostr private key) into both apps or import it into Alby to use on Primal web. Mutiny is a bit more complicated but it too bad. You'll just need to send funds to it and a portion of those funds will be used to open a Lightning channel. Make sure you're sending a large payment as your very first payment to Mutiny. The larger the better.