Cross-posting is one of Lemmy's greatest features. Though I would suggest you limit it to three posts. One of the greatest things about cross-posting is it enables people to find new relevant communities, so I would suggest posting from smallest to largest.
Lemmy Support
Support / questions about Lemmy.
Thanks, I see that the cross-posting works like this: "In order to cross post, I need to first create the post in one community, then after I create the post, I can click the two nested squares icon under the title of the post (with the pop-up text “cross post”) that shows up on mouse-over." https://lemmy.world/post/354611
Use the crosspost feature. Some frontends can even filter out those someone has already seen.
I can't speak for the policies here, but just from a etiquette perspective as long as their cross posts so each of the communities can see where else you've posted it I think that's fine. Then if people are really interested in the discussion we can follow it
Sure, but try not to appear as a spammer.
When an episode of Taskmaster comes out I usually post it to taskmaster@feddit.uk and Britishtelly but no further.
Unlike some people who are currently trying to spam the 'reprogram your brain' video in 6-8 communities