Reading this thread, you seem to be really lost. First of all, Mastodon is not the whole Fediverse. That's your first mistake. There are many other platforms that interact with each other. Maybe the features of Mastodon are not the ones you need, but the ones offered by those other platforms are.

Discoverability: How do you think I found you if you were not discoverable? Do we know each other? No, but someone shared a link to your thread and then I searched for your nick. It's that easy. Other people have mentioned hashtags, so I won't repeat that here. It's long enough as it is, but I'll add some examples you might find useful:

#africa, #blackFediverse, #blackAcademics

Full text search: That was a technological decision. Full text search is very expensive on self-hosted servers. It is possible to have it (the instance I'm in has it), but it's not for everyone and it's not really needed. Also, it's not safe. I wouldn't want people to find old posts of mine and use them against me.

QT: Some instances have them, other platforms (like Misskey, Pleroma and their forks) have them. If you really need them, there are options. I'm using one right now to reply to you.

My advice would be to find someone tech-savvy and ask him to help you create an instance of your own, then invite your Twitter community to join you and re-start from there. To be honest, mastodon.social is probably the worst place for a newbie (no offense) to be.

Hope that helped.

cc\ @naunihal