Thank you for your inquiry.
1) Will members on the same tier be able to purchase access to specific pages they pay for?
Yes. Any member or nonmember can use Specific Post/Page Access Buttons/Pro Forms to buy access to a Post/Page, or you can sell this content with Custom Capabilities.
See: Dashboard -› s2Member® -› PayPal® Pro Forms -› Specific Post/Page (Buy Now) Forms
See Also: Dashboard -› s2Member® -› PayPal® Pro Forms -› Capability (Buy Now) Forms
2) Does s2member have any options that can show customers which pages they have access to?
s2Member doesn’t have any specific functionality for this purpose, no. But s2Member does offer several API functions that would make setting this up much easier.
See: http://www.s2member.com/codex/stable/s2member/api_functions/package-summary/
3) Does s2member handle guest AND member page purchases?
No, s2Member currently does not have the capability to perform guest purchases. Sorry about that.
4) Is the built in WP member directory good enough to retain s2member customer info?
This is what all of s2Member’s installations use, and it works just fine for our users. It’s meant for holding data like this, so it should work fine. :-)
5) Are there any other membership databases that work out of the box with s2member besides Buddypress?
You can find all of our integrations here:
s2Member® » Pro » Features
6) Is there a way to show certain members ads and pages we want them to see?
You can use other plugins to achieve this, as s2Member integrates with the default WordPress Roles and Capabilities functionality, so it integrates smoothly with most other plugins in this regard. s2Member doesn’t have this capability out-of-box, though. You’ll have to set this up on your own.
7) Can we use a normal front end header login plugin or does the pro version have one? (built in the header only)
You can use a normal login form with s2Member. s2Member Pro does come with a login widget, but it’s meant to go into a sidebar.