For those struggling to wean yourselves off Reddit, someone has made a bot that copies posts from subreddits to Lemmy so you can follow the subreddits from here. I made a post about doing something similar a couple of weeks ago.
They have their own instance at lemmit.online. The r/newzealand is clone is at !newzealand@lemmit.online.
Most of the communities there aren’t showing up in the search here without the full link yet, so go to their list of local communities, open a community you want to subscribe to, then copy the link that looks like !newzealand@lemmit.online from the sidebar into the search on Lemmy.nz (or your local instance). If the subreddit you want isn’t listed on lemmy.online, you can post a request in !requests@lemmit.online. It was pretty much instant for me.
Personally, I think it’s fine for people to cross-post stuff they think is relevant to the communities here. I’d prefer it over links to Reddit, because it lets people engage with the content here. I doubt posts in !newzealand@lemmit.online will get nearly as much attention as the ones on lemmy.nz. The Lemmit bot makes it pretty obvious that it’s taken from Reddit. I think one guideline would be not to remove the bot’s text from the post, nor the “cross-posted from” text that’s generated when it’s cross-posted here.
As for question posts, it would be a weird thing to cross-post. I guess if someone wanted to give credit to the OP on Reddit. I can’t see that happening too often, unless it’s a pretty broad question that generates discussion - in which case, it doesn’t seem to matter to me if there’s a separate discussion going on here.
I think just posting the content (headline and link) here would be better than posting links to the reddit discussion.