Investigate migrating EASE project from gerrit to gitlab

With the plan to shutdown gerrit instances in the near future I would like to plan to move the EASE project to gitlab.

Currently I have a few questions:

1. does a default setup already help in setting up connections between gitlab and jenkins (eg to trigger builds on commits/change requests)
2. EASE comprises of 2 source repositories. Instead of mirorring them to gitlab I would rather like to merge them into a single repo (keeping the history) and to migrate this merged repository. Is this possible?
3. will the website git repo also be moved to gitlab?
4. What about the wiki? Is it intended to move mediawiki pages to gitlab, too? Is there some kind of importer available?

thanks for your input!