By far the most important thing is doing Gem Gacha every day and getting one element full on slvl20 SR Assault weapons (or better). That is the STARTING point of Kamihime.
Andromeda is a newbie trap. She seems great, but sadly, she is not particularly useful. As soon as you reach the above mentioned starting point, you'll do enough damage that heals will be far, far less useful for you. I highly recommend you stick to my guide, which is Gawain -> Cass -> MORDRED, followed by Dartagnan/Herc/Joan in whatever order you feel like.
However. Since you're below rank 50... ... it would also be extremely good to reroll into a 100% or better Eidolon. Aim for Cerberus/Leviathan/Hanuman/Nidhoggr, maybe Managarm/Anubis. Yes, that means throwing all of your progress so far into the trash bin. But trust me, it is VERY worth it. Trust me, trust me, TRUST ME. Seriously. It makes a HUGE difference, both right now and far, far, far into the future.Sadly, I do not know. When Labyrinth event came out, it was such a breeze for me that all mobs just fell over. As such, it is difficult for me to understand your pains...
Anyway, higher levels have bigger chest bonus, which means less AP spent to get treasures. But if you're struggling, it might be better to farm lower levels and just keep moving up until you hit a wall.
All events are always worth farming. Remember, everything you do will make you stronger. The main weapon this time around will be really great for Medea builds come April 2021. Even if that wouldn't apply to you, there are lots of other neat stuff available from the event such as Jewels.I was at work!
I don't really have much to correct. Except you spelled my name incorrectly (twice) and I think you're jumping ahead quite a bit. I doubt he needs that much of a list of things to do just yet~