In regards to KP there seems to be a maximum limit. Once you have unlocked all resources, killed all creatures to 100%, killed all legendary creatures, visited every city/city resource you will be capped.
However, if during your adventures you have "unlocked" certain abilities and no longer need those abilities because your build concept has changed you are at a net loss in KP.
Please allow us to "lock" back "unlocked" abilities to refund our KP so we can use those in our final builds.