> I do have a repertoire of 'how to save and curate content that was made on Web 2.0 platforms' skills, would you appreciate a description of some of them?

Thank you for your offer of help. I've done a lot of archive.org diving and I do have most of the art on my hard drive. The thing that I lost and mourn for are all the notes on my posts, and unfortunately, I think the only way to get those is to find the one post that someone reblogged. And hope that that post hasn't been deleted, or that person hasn't changed their username or got deleted by tumblr like me...