Cracks knuckles- Derek and John are major CI folks, so hopefully they’ll chime in as well. I’ve dabbled a bit and found CI easy to pick up, no doubt due to the shared brains behind both. I’m not sure how it would be coming from CI to EE, but I’m betting it would be fairly easy. Still, it took a logic shift for me, so that may be the case for you as well. Just don’t make assumptions and do read over the docs. You should be fine (you might take a look at the developer docs- bottom of the linked page- good way to get a quick feel for the logic behind the code).
2. There isn’t an existing module/plugin to give you that url structure for the forum. In truth, I’m not recalling much discussion of it around here. A quick search turned up this post and I vaguely recall one more. But the short answer is, you might need to build this one yourself (or hire it done).
3. Yes- see the developer FAQ and license for details.
4. Simply having adsense/amazon links/affiliate links/etc isn’t a problem and doesn’t prevent you from using a personal license. If the main point of the website is to support a business, either directly or indirectly? Then you need a commercial license. You can always check with sales if you’re uncertain which license is appropriate.
5. Depends on how you want to do it, and if forum posts, wiki entries, article entries, comments- etc- are all going to be mixed together and have one ‘trigger’ for inclusion. That might take a bit of custom coding- but it really depends on what you’re wanting to pull out. If none of the types of content are going to require the addition of fields that don’t exist, then the query module is a highly flexible way to pull in specific data. So short answer- it depends.
6. No, there isn’t an existing importer. However, the EE wiki has a nice rundown of a manual PHPBB Import that might be useful. And I do know folks have imported other types of forum- but it’s going to take some manual work and a fair knowledge of both databases to do it.
Does that hit the basics?