2
1. Yes, comments can be displayed in nested, threaded or flat views.
2. I haven't seen one.
3. Search for 'blog' on this site, there are several different modules you could use.
And as a 'by the way', there is no built-in forums in XOOPS. The forum module that is included with the current stable release is only one of several forum modules available for XOOPS. Further XOOPS releases will only include modules performing core functions ( no forums module
) and will instead have recommended packages of modules for specific purposes.
For a forum module my personal choice would be CBB, it's built for XOOPS, is actively being developed and has excellent support.