Hello,
1. yes, DotNetNuke can exist in the same database as existing objects. To stop object collison i.e if the database had an existing object such as a table called "users" which DotNetNuke would look to create, we support the ability to set an objectqualifier (
http://www.dotnetnuke.com/Resources/W...) - this would mean that if the objectqualifier was "alan" all objects would use that e.g. tables would be called "alan_users", "alan_portals" etc.
Now, thats just to coexist with your data, dotnetnuke will not know to use it automatically. As the data exists within the database dotnetnuke is using you can now write modules to work against that data easily, or write an authentication provider to validate users against, or just use a module such as the reports module to execute queries against it.
2.Yes, All versions of DotNetNuke will work with Sql 2005 (both express and the full product) -in fact from DotNetNuke 5.2.0 SQL 2005 is the minimum version we support, prior to that we supported SQL 2000/MSDE 2000 on all releases.
3 You can view the current html editor provider video at
http://www.dotnetnuke.com/Resources/V... -it does support custom configurations of what options are available and allows binding to portals/pages.
4.yes, dotnetnuke has rich support for security roles and permissions, and allows for grant and deny on individual permissons at both the user and role levels.
5. not out of the box - the core html module does allow for dual stage processing (i.e. content staging) that has to be released by the approriate person and also supports rollbacks, and the professional version has full workflow (but is not free). There are a number of free modules that implement full workflows also.