Hi Daniel.
I’m answering your questions below. I’ll try to keep the replies to the point to make them easier to read on your phone.
-group rights are usually independent of others, no hierarchy of different levels, is this supported?
The s2Member Levels do have a hierarchy, but if you need to give access independent of others you can use custom capabilities. Video » s2Member (Custom Capabilities)
It’s not impossible to avoid the hierarchy in Levels, though. One way is checking the user level with conditionals, instead of protecting the whole page at a certain level.
[hilite path]Dashboard -› s2Member® -› API / Scripting -› Simple/Shortcode Conditionals[/hilite]
[hilite path]Dashboard -› s2Member® -› API / Scripting -› Advanced PHP Conditionals[/hilite]
Another -less common- way is customizing the s2Member Level roles to remove the capabilities that give access to lower levels. http://wordpress.org/extend/plugins/user-role-editor/
– can user be in more than 1 group?
If it’s with levels, no, but with custom capabilities it’s not a problem.
– Restrict page/folder by group?
You can protect pages/posts with custom capabilities. The edit page for each post has an s2Member box where you can enter the ccap(s) you want to require for it. Or you can use conditionals in the post itself, or a hack, to check if the user has the required ccap(s).
By folder, do you mean a directory with files? If so, yes. [hilite path]Dashboard -› s2Member® -› API / Scripting -› Custom Capability and Member Level Files[/hilite]
– restrict part of page by group?
Yes, with conditionals.
– verify username/ pw via web service / mobile app?
Well, the user login is still handled by WP itself, it’s not touched by s2Member.
There’s this video that talkes about remote authorization for podcasts, but I’m not sure if it’s pertinent to what you need: [hilite path]Dashboard -› s2Member® -› Download Options -› Remote Auth/Podcasting[/hilite]
– db table schema, does it use wp user and usermeta tables?
Yes, s2Member uses WP’s tables only so far. In the future this will change to overcome many limitations it creates, though.
– how does reoccurring billing work?
That’s handled by the gateway. You create the button/pro-form for the transaction, and there you specify what the recurring details are (term, amount).
[hilite path]Dashboard -› s2Member® -› PayPal® Buttons[/hilite]
[hilite path]Dashboard -› s2Member® -› PayPal® Pro Forms[/hilite]
[hilite path]Dashboard -› s2Member® -› Other Gateways[/hilite]
– no problem adding other tables and referencing user id?
The user is created the same way by WP, so you can keep using interacting with the WP users as usual in your customizations.
Does that help? Let us know if you have more questions. :)