30fps is perfectly fine for submitting, by "reasonable quality" its more or less so that A: we can see the core things needed to submit (timer, version, which is affected by resolution) B: It isn't freezing or unwatchable. Unwatchable would really mean something like 5fps, but it is an opinion. I would consider even something like 15fps to be watchable, but trying to stay at at least 30 is perfectly fine, as it really depends. As for OBS settings, there are probably a plethora of guides on youtube for that.
Welcome to the speedrunning category!
Please make sure to read rules, as all the rules from there apply to here (especially read rule 9 before commenting on someones PB in pb_posting).
If you're looking to start running Celeste, check out https://www.speedrun.com/Celeste/guides and https://www.speedrun.com/Celeste/resources. If anything is unclear, ask and answers will come.
A collection of various resources and guides can also be found here: https://docs.google.com/document/d/1BXmnx93pkX29jAVzE1CmVZpiJilAn9vOEgaYtwLyBs0/edit?usp=sharing
Additionally, we have an FAQ that also serves as a guide, it answers questions often asked and is highly recommended if you're just starting out: https://docs.google.com/document/d/1reV5XmTicyMVGeQvYvEPqAL8YSpidnzA09DFjIUmd34/edit?usp=sharing
If you want to practice-race with other players, give yourself the racer role in roles and keep an eye out in racing, or host a race yourself.
Official speedrunning leaderboards: http://www.speedrun.com/Celeste https://www.speedrun.com/Celeste_Category_Extensions https://www.speedrun.com/modded_celeste
Playlist of Celeste TAS Videos: https://youtube.com/playlist?list=PL3fCdq8PkmBzDeg36Hrgk1CLUd_raEq9S