As a caveat, Guidance would have a single person it can be active on per source caster limit. I don't think it should be active in combat; it seems like its intended purpose is for proficiency checks.
And Bless/Mirror Image pre-combat should be removed by making it so temporary buffs run out in a second or two outside combat to discourage prebuffing. In turn, Mirror Image could be moved to a bonus action costing a spell slot, and quite frankly so should Bless and most utility buffing spells that cost a spell slot.
