(if reply with quote doesn't work, click it again... seriously. :) has happened to me, but the forum software has been setup/revised to go to a new screen instead of sliding out the entry box. Anyways...)

I believe each of the items asked about (for the like 98% of it) are fully covered in the instructions.

So, start on the first page of the documentation. There's a link about "mid-screen" where it says something like if you're having problems read these FAQs.

So, then the first issue about getting 404s. There are at least two topics with that in their title and the link for each goes to a slightly different discussion, but they are both of value. It appears that you've followed the rabbit trail at least to the discussion of the rewrite rule modification so that you can allow the plugin to manage an address ending with .html. So that is part of the aspect.

Pretty much the rest of the questions/issues are how to let the software know the destination of a provided url that has been used from outside of the software. This is something that is covered in the configuration section of the manual at or around section 10.