Hi, I hope I've posted this in the right place. I recently picked up this game. I'm having a ton of fun with it, but I can tell that since it's such an established game already, it'll take me awhile to digest the information. I'm doing my best to make sure I don't make any big beginner mistakes, but I thought I'd post here to be sure (I've seen the stickied beginner guide). Here are my concerns:

Right now, I'm stuck at Tomb of Sorrow. The enemies completely overrun me, and I suspect part of the problem is that my units are too weak. Most are in the 10-15 range, though Katie is a bit higher at 25. My question about this map is this: do I need to sit back and grind for a bit, or is the problem my lack of skill? I definitely know that I haven't quite grasped how to play optimally yet.

Regarding grinding, I've read that Pastoral Gate is the best early map to play through. Is there any difference between manually playing the map, and commissioning a sortie? Finally, I understand that one of the keys to getting CC'd units is being able to beat the Monday daily H difficulty; what are the steps I can take to secure that goal as quickly as possible?

My goal for leveling and affection priority is roughly Katie, Iris, Bashira, Cloris, and Grace (I rerolled until I got a black unit within 10 SC), most likely in that order. Are there other units I should emphasize instead of these?

Finally, how concerned should I be with the current Dark Guild's Servant event? I've gotten 3 stars from the first mission, but got absolutely slaughtered on the second one, and haven't wanted to retry it because Stamina is such a precious resource right now. I assume I should attempt to get any and all SC I can from timed events, but I don't want to waste resources doing it that might set me back in the long run.

Is there anything else that I should be aware of? Thanks for potential responses. I genuinely appreciate it!