This instance, like most instances, would prefer most content come organically, rather than just being a mirror of whatever reddit has.

I'm not against it as long as I can avoid reddit taking over my feed. I'm happy to get away from reddit, not just because of their business practices, but the culture has changed to something I rather avoid. I'm liking this cozy federated feel so far and would prefer to keep reddit's culture from taking over my feed again.

Well there is a tool that uses the API for this purpose https://github.com/rileynull/RedditLemmyImporter Maybe one of the little niches carved out for free API use, like for bots or something might work for that, but definitely should work now.

Another interesting idea is for getting historical data, pulling it from the archive.org project from the project r/datahoarders are doing now.

I think that would be great. There's a wealth of posts and comments that users have made that deserve to be preserved and shared. It would help Lemmy grow and just be a good policy to make sure Reddit doesn't control access to the content those users generated.

As long as you link or referce back to the post and user I don't see how that would be legally or morally problematic. It's all public anyway, but IANAL so this this not legal advice, just my thoughts.

If you are talking about your posts there is no problem, but if you are talking about all the posts and replies of a subreddit, I think it is a bad idea as you are replicating comments and opinions of other people who couldn't delete them in a future if they wanted.