We have over 1000 Tridion specific questions on other Stack Exchange sites. Is it possible to move them to this site to prevent duplicate questions?
While it's technically possible to migrate questions, the migration paths are not set up until a site becomes well-established. But beyond that technical limitation, building this community from the old, pre-answered questions of another site would do this site a terrible disservice. That's not how you want to build this site.
Forget for a moment that other sites may not want their content removed like that (along with the the knowledge and reputation earned). Consider that, from day one, your brand new site will be filled with old, pre-answered anonymous questions, as the original authors are off on another site. Your tags will be inherited from another site, regardless of how this community wants to organize content here. Comments would be largely meaningless and scattered with links to another site. Voting wont reflect the activity on this community, which makes it difficult to build an avid higher-reputation community to watch over this site — Vote Early, Vote Often.
The idea of creating a site dedicated to Tridion is to build a community was supposedly not being well-served by another site. I wouldn't rush to simply migrate a lot of old content. Focus on building your own community. Give yourselves some time to figure out the scope and culture of this site. You should focus on building your own content with properly curated content, built with the community and expertise that genuinely belongs here.
That was the point of creating this site in the first place.
How to migrate question to programmers.stackexchange.com indicates it is possible to migrate questions, but this site needs to be public first so it looks.
Which means we will have to go over the existing questions when this site goes live (if we feel that is appropriate). At that point we could also migrate the new questions being asked there (which means vote to close them as off topic). At the time being there isn't much we can do with preventing new questions from being asked in other SE sites.