All the information comes from the CN cbt3, the beta has not started yet for Global.
You can spend really money in the beta. And you will get gacha currency back when the game full release, the amount depends on how much money you spend in the beta.
The primogems are used for exchanging gacha currency, Intertwined Fate (for limited banner) and Acquaint Fate, 160 primogems for 1 roll. You can get primogems from shop and farming, like completing mission, opening chest, etc.
In the gacha system, every ten consecutive wishes will receive at least one 4 star item (either weapon or character). 90 rolls guarantee a 5 star item (either weapon or character).
=Wish Rules=(from google translate)
The base probability of a 5 star item wish is 0, 6%, and the overall probability (including a guaranteed floor) is 1.6%. A maximum of 90 wishes must be able to flow over the guarantee to obtain a 5 star item.
The basic probability of wishing for 4 star items is 5, 1%, and the overall probability (including the guaranteed level) is 13%. Up to 10 wishes must be able to get 4 stars or more through the guarantee.
When rolling a dupe character, you will get a corresponding constellation for activating passive skill.