Fun fact: while not being exactly like what karma was on Reddit, Lemmy does store the total count of upvotes-downvotes your account has received. You probably can’t see it because it isn’t shown by the frontend (the website you see), but the data is indeed there.

Ansible guide. I didn’t follow this one myself but the guy who set up my instance said it was pretty easy
https://github.com/LemmyNet/lemmy-ansible

…or join a smaller instance.

Same, since I updated my instance to 0.18 Jerboa doesn’t work and instantly crashes.

Upvoting this post from Connect for Lemmy. Actually I think I still prefer Jerboa. Unfortunately it has stopped working since I updated my instance to 0.18 so this will have to do for now.

This. Defed is not the magic weapon that will solve all your problems. Captcha and email filters should be on by default though.