Confused about Add-in "SAAS" and Offer types.

Question

Hello,

I have been reading the certification and AppSource requirements for developing Office Add-In's. I'm a little bit confused about some of the policies.

My situation:

I'm developing a Microsoft Office Word add-in that is generally targeting organizations, but would still like to enable individual users to have access in the event that their organizations do not sign on to the add-in.

I am hosting my own user management solution off site that will be used to provide access to the add-in (you must log in to use the add-in or you will not be able to access functionality). I will be charging users / organizations (outside of the Microsoft / Azure world) to have an account with my service. This will all be done on my side of the house, the add-in will integrate data from my web service into Word for use with document drafting.

Question:

Can I simply list my "app" as a free application that users can download, but they are required to set up services on my web site before use? In this case would Microsoft govern how I charge for access? I read policy around SAAS where it stated that you cant change your pricing for existing users, just for new users etc... Does this only relate to if you have paid plans on the "Offer Listing" as opposed to your web service?

I'm confused because there is "SAAS" in the traditional sense, and then "SAAS" Microsoft Offers which speak to certain percentage of your application being built on Microsoft services etc...

Also, if you choose not to list in "AppSource" but deploy from integrated apps via link to manifest.xml file, does it require the same certification and validation policies?

Thank you,
Curtis