1) yes, unless you're somehow filthy rich (like 3mil gold +)
2) more or less, yes. I would classify them under similar priority, not sure what tenhou thinks though.
3) for me, yes. I doubt I'll ever use Uzume/Sakuya under normal circumstances, at least. cost too high for what they can offer.
4) no, considering you have mincosted phyllis. (Phyllis when you need low cost multi-blocker, Cypria/betty when you need to simply thin the waves, aka take them out one by one)
5) Both yes, but I won't say skip Lilia. She can wait until after those 2, but it's worth maxing her eventually (She is amazing now, and can be even better after AW)
6) Preferably both, but probably Odette 1st since she's easier to use, aside from her cost.
7) Yes. You should consider them after all the core units we mentioned before, but these 2 are basically useful for specific situations and fun to play with later on. But not very critical.