Quick general notes:
We're not planning to set up wikis for "shared", "wts", "assoc" or "general" on the WMF side of things.
1) WV e.V. is going to keep the old sites available in read-only mode under an alternative URL for at least a month or so, so there'll be time to fix stuff that's broken or missing post-switchover.
WV e.V. continues as an independent nonprofit organization and will continue to host the wiki for association purposes ( http://www.wikivoyage.org/assoc/Hauptseite ).
2) Wikimedia projects have a single media repository for freely licensed files, Wikimedia Commons.
Correctly licensed files on "shared"/"wts" should be transferred to Commons. This is a process that's best organized by the community as licenses have to be vetted, templates adapted, etc. If a file is uploaded to Commons under the same name under which it was previously uploaded to WV, then it should "just work". If it needs to be renamed to avoid naming conflicts on Commons, then pointers to it will have to change as well.
As has been noted, non-free media can only be uploaded locally, and only if a wiki has an "exemption doctrine policy" as per the WMF licensing policy:
https://wikimediafoundation.org/wiki/Resolution:Licensing_policy https://meta.wikimedia.org/wiki/EDP
3) The "general" wiki does not contain a lot of pages as far as I can tell. We have a single "meta-wiki" in Wikimedia ( https://meta.wikimedia.org/ ) and to the extent there are cross-language pages that affect a specific project, they're typically organized via subpages, like so:
https://meta.wikimedia.org/wiki/Wikibooks/Logo
and/or via categories. So I'd recommend just copying the few pages that are there over to Meta manually with proper attribution.
All best, Erik