how people find accounts they like to follow.
The low-hanging fruit is sometimes checking out posters that show up in your feed because someone you do follow boosted their post. This sort of amounts to having the people you follow nominate people for you to also follow.
(fwiw, boosting a post just shares it to your followers, liking it just notifies the poster that you liked it)
Yes! your fedi client will spit out a text file (.csv format I think) of accounts you follow, or of accounts following you and I forget how many other kinds of information (like block or mute lists, etc). You can share that with others, or if you decide to migrate to a different instance, you can use that in your new account to automate following of everyone you followed in your old account.