I suspect there will be a lot of customized stuff that we end up with when we actually do the import (though to be fair, while I think NodeBB is our leading candidate, it's not a done deal yet). We did a partial import from CS to Discourse, so a lot of the user deconfliction has already been worked through.
Most of what we do seems to be non-traditional.
use nodebb-plugin-write-api and you can create how many post you like using ajax instead socket.io
PS: creating your own posts doesn't mean your site will be any good. It will look "not poor", but it will be anyway.
You could make a custom icon just by making a new class in the css file something like
background-position: center center;
width: whatever maybe 16px or 32px
height: same as what you put above
Or you could make a custom font file
In NodeBB, subcategories are referred to as child categories. In order to set up your subforum, you would create your necessary categories (one for mobile phones, and then others for android, ios, etc) and then set the parent category of your intended subforums to be your mobile phones category.