OK...I've opened 1 extra door so far - Command (it's 1st door) - on my Guild Flagship. How many doors does it have and do I have to open All of them before I have access to the Perks? Thanks!

I would gladly spent coin on a Legacy Perk where you are able to access all your Toons mail in one spot. You wouldn't need to log into each individual Toon to get your mail.