Fresh WP install, but I want to migrate all my blog posts

Hey good people,

I'm giving it a try in this forum, hopefully getting some smart thoughts that I haven't been thinking about myself yet.

I got my website and blog running at Motion-effect.com.

This fall, my team and I are doing a re-launch of my site. And to do that, I have set up a new one from a fresh WP install, building the site using Divi 3. And the site has been built at a sub-domain, using "2016.motion-effect.com".

The remaining thing now is to move all my existing blog posts from my old blog to the new 2016 install. I tried once by just testing the basic WP export/import, but a bunch of images is missing. Especially Featured images have been detached it seems.

Here's a few questions/issues.

• What's the best tools to migrate blog posts over to a new blog?
• I would like to change my Permalinks in the new blog, how to best handle that regarding my existing Google search indexing?
• The new site will have SSL/HTTPS
• Some categories will be rearranged, should that be done before the import of blog posts, or rather change permalinks after the import?
• Let's say I export and then import blog posts using the same URL/permalink structure (so not to lose Google linking), and then change the Permalink structure after, on the new site. Will WP keep a record of that? (old URLs to new URLs)

I have transferred a lot of sites, but not moved blog posts only.

Happy to get some new brain-feed on this.

Johnny