Character IDs can be found by hovering over the relevant character, whilst county IDs can be seen in pink text when hovering over the county. Christian religions, particularly Catholicism, seem very underpowered especially in 867.
CK3 cheats can do a lot-just by typing a few console commands you can make yourself rich, There is a 'Other Faiths' button just under where it tells you the current fervor.
The purpose of this mod, as my first for CK3, is to bridge the gap between CK3 and Imperator:Rome.