Changing Transfusion characters and resource recovery after level reset

Apologies if I missed this, but is there a way to swap the characters used for transfusion? I would prefer to swap in breakthrough SSRs (started with SRs to reach the 160 cap comfortably) to free up slots.

Secondly, if I reset the level of these SRs, aside from spending blood, does this recover all resources spent on leveling up? I read that the money is lost but haven't tried it myself. Thanks in advance!