Hi Daniel, in response to your questions:
1) Our themes are not set up with RTL options within the admin, so it does require some customization of the default theme which is technically outside of the scope of what is officially supported. In saying this, there is existing WordPress documentation available for
right-to-left language support, as well as discussions on this topic in our support forums from members of the community. In cases such as
ClassiPress, one of the theme translators also provided an RTL stylesheet with the Arabic translation to help others in this position, which may help as a reference of how it's done also.
2) In the "advanced" tab of the
ClassiPress admin settings, you can find a specific field "cufon font replacement" setting area. Not all themes have this option already available in the admin this way, but essentially you could work it in with customization if you needed to.
3) Products available in our marketplace will have an indication in the sidebar as to what themes are compatible, and so far I believe the ones we have listed are designed specifically for AppThemes products, hence not likely tested with other themes. If the plugins are not AppThemes created, then there's always the opportunity to post a comment on the plugin page and ask the author more.
4) All of our themes require the user to be registered before they can post an ad/listing, so if this is attempted by someone who is not logged in, they are taken to the registration/login page to proceed.
5) Security is more related to WordPress and your own hosting setup than the themes themselves. You can find some useful information in this
WP documentation on this topic.
6) There are no discounts available for items in the marketplace at this time.
Thanks :)