Varjik.
There are plugins for both private messaging and a WYSIWYG editor.
BBPress does work well with WordPress, better than any other forum software. What people like you fail to understand is that whilst, relatively, integrating BBPress with WordPress is easy, it is not something a basic WordPress user who does not have any knowledge of PHP should really do, unless you are prepared for the challenge and prepared that you mgiht not be able to do it.
Regarding themes, you need to edit the BBPress theme you are using. You need to add the Get_Header and Get_Footer tags of your WordPress theme to your BBPress theme files. If you wish to use a sidebar you will need to reference the sidebar too.
You then need your Forum to fit in the Wrapper of your WordPress theme, you do this by referencing the wordpress themes CSS wrapper in the BBPress themes files, using div tags.
You also need to then make sure a copy of your BBPress CSS is in the same directory as your wordpress CSS, you then need to reference the BBPress CSS in your wordpress header.
If you know what you’re doing with web design then those steps should be fairly easy to follow. At the end of the day, a certain level of expertise is required to integrate BBPress with WordPress.
I have managed it, you can see the result at:
Discussions
As you can see, both the WP site and the BBPress forum use the same theme.
Personally, I think if you are already looking to phpNuke then WordPress is probably not for you. I personally think phpNuke is the poor mans WordPress, it’s gimmicky and performs poorly, but if that’s what you find easiest then it’s whatever you think is best