Pincushion works perfectly with Bloss but goes well with Adlay too. And I guess she can be used with any girls with Retain HP. She is basically high risk high reward but as long as you keep your HP above 100% (not that hard with Adlay) she is an incredible support.
I'm pretty sure she can have a place in evade teams too. I don't know if she is worth the stones but at least, she is not a total waste.

Boronia looks a bit average (would be better with combo hit insted of pursuit). She lacks something to really stand out. I guess she is too old despite being a loli.

You should be able to get at least 35FG this week (14 from the new event, 15 from weekly gems and 6 from 300% on the new girl). Maybe more if we get the permanent Decisive Battle with Midgardsormr (I don't remember when it's planned, I guess it's somewhere in May). And you can get even more depending on how much girls you have with 0% affection and personnal quest not done yet.

I guess Adlay will came back soon. she is the next one on the Ancient Knight list. Just hope that devs don't realese all the others limited girls before... or realese Adlay/Garden Phlox/Tacca too close (this would be the worst).
I think she is the basic must have now. I hope she will came back soon but not too soon before you can get 500 FG.

For Jack, you could try focusing on Blossom Hill for world research. Not like it works but it could increase your chances a tiny bit. Or burn a LOT of salt tickets and pray. I somehow always get all my missing 5* when I burn them at the end of the year (but I use like 3k).
Sadly I think devs will only give 22 stones on gacha now. Anyway, you may get her before Heart Tree came back.


And for the teams plans, that's so hard to tell. there is so much options, so much potential new hardest stages in the future and things evolve way too fast. In the past a good team can stay good for a long time but now, a good team today can be outclassed in a week.
I think, you should focus all on Adlay and once you got her, think about the meta at this time. If she cam in a month or two, things may have changed a lot with Khepri friends.