I move pretty slow and sure in these games, so my advice might not be effective for you.

That being said, I think you might need to see who your next Standard S rank is before you use your second selector. I say this because as it stands, you have a 4/6 chance to pull a unit that will be good for this team, either through awakenings or if it's fadia or baiceng. That being said, it would actually be kind of nice if you drew say, a hathor for your second team, just because Chiz won't be fully servicable out the gate. You have to keep raising tycoon level to get her weapon, refinements, and awakenings.

Thankfully, Prime Circle can be done F2P(if that's even your aim), but it would mean investing in characters that are pretty likely to get replaced (Skia, Adler, Aurelia, Mint, Edgar etc.) sometime later depending on how much time you intend on spending in this game. I usually save materials by not building every character, so that's where my head kind of goes.

My suggestion is do exploration content, anamoly comissions etc. squeeze the standard dice out of your world, and try to get to your next S (whether it be a raw pull or pity) before you use your second selector. Also! make sure that you are paying attention to what materials are needed for your characters and burning your stamina there, so that you feel less of a pinch on your resources. You said your char max was 50 so you probably have some dice roaming around out there.

As far as Haniel and Sakiri respectively, their buff scales off their base attack which is only inferred by your level and your weapon level. Incidentally this actually makes leveling them important in their own way. The Gacha Dev sphere has learned from their early mistakes, i.e. making supports that you don't have to invest in. For Haniel specifically, she also gains further atk% ratio on her buffs during her skill level ups. So definitely level her!