Customer Portal Add-On / Is this per "App" or per "Account" / what about sub-domains

Customer Portal Add-On / Is this per "App" or per "Account" / what about sub-domains

Hi there,
I would have 2 questions regarding the " Customer Portal Add-On"... as I'm just not not sure.

1. Is the Customer Portal Add-On per "App" or per "Account"? I see that within each App (under the same account) I can go to Customer Portal and see the provided URL is different. Clicking on that also sends me to the Login Page. Considering this, I would assume that that once you have the "Customer Portal Add-On" (for the 99$/month) this feature is now available for your ACCOUNT, i.e allowing for a new (different) Customer Portal per App. Thus, I could have 5 Apps and 5 separate Customer Portals with the 99$ per month... is this correct?

2. Following on from my question above, I can add my own Domain URL for these Portals (given that I contact the support team in regards to the SSL issue etc...). My question now is... can I use sub-domains? Example: could I have www.customportal.com/customername1 and www.customportal.com/customername2 etc.. or must it be a main domain name ( www.customportal.com ) ?

Hope someone can advise?
Thank you in advance.