I would suggest you watch some videos. There are some older ones which you find on youtube describing the basics of the game. 

Your questions are on one hand too specific to correctly answer... ont the other hand too complicated to answer. 

Just a quick one: Bring Elhain to 60 to farm 12-3 brutal to make food. Ronda and Genbo are good in specific settings...do not invest too much in the other champs at this time.

Is any of your champs 6* right now? If not, Athel may be your best choice. She is a decent campaign farmer, and that is definetly the first thing you need to 6*.

Forget about tier lists for now. The overall rating of a champ doesn't matter at the start of the game. What a champ is able to do in DT hard or Hydra becomes interesting when you do this content of the game. The first things to start are getting a campaign farmer, to make more champs lvl 60 in reasonable time. Then, get a Dragon team to run for your basic equip.

Tier lists are only a guideline, not laws carved in stone. If you compare different tier lists, for example Ayumi and HellHades, you will find that the latter gives only 15 champs a perfect 5 overall rating, while Ayumi has allready 47 legendaries rated S-tier. On the bottom end, Ginro the Stork is the only legendary who is ranked in the worst 10 by both lists. There are 19 diffent picks for the worst 10 in only two lists. Wich of these tier lists is right and wich is wrong?