Which instances of Mastodon or similar platform would you recommend to post NSFW stuff and how can I repost that stuff to a Piefed community? NSFW

If you mention a community in a Mastodon post it should appear in piefed no problem. First line will be the title / subject line.

I don't know how piefed and similar handle multiple media (default Mastodon allows four images)

Erome is a good place, but use Adblock.