

Lemmy dev here. Making the same post to multiple communities is not possible, so you need to post multiple times tagging a different community each time. Links are taken from Activitypub attachment, but Mastodon only seems to support image attachments. So it is not possible to add other types of links unless Mastodon adds an option for that. Markdown would also have to be supported by Mastodon.
There are various other microblogging platforms on the Fediverse which may support these features and may be better suited to your purpose. For example Mbin, Hometown, Pleroma, Misskey or Mitra to name just a few.
Algorithms are definitely needed to discover good content. There are some good videos on Peertube, but its very difficult to find them due to all the low effort spam. Lemmy also had different algorithms from the beginning and no one ever complained about them.
The problem with algorithms used by Reddit, Facebook etc is that they are completely intransparent, and include factors which dont benefit the user, such as “engagement” or advertising. As long as Fediverse algorithms are focused on benefitting the user and are transparent there is nothing wrong with them.