I’ve made an app that makes it possible to schedule a post in Lemmy at an arbitrary time. It’s available at https://schedule.lemmings.world and can be used by people from any instance.
Let me know what you think!
P.S. This post was made using the app!
Edit: And it’s open source!
Not currently, no. You can post pictures by uploading it somewhere first and then using it as a link.
If more people use it and want that feature I’ll consider it, but so far it’s not planned.