1) As the app allows you to add several photos per person, maybe add an option to not select a primary one but to have the the app pick one of them at random and display that one in the tree.
Already discussed in
https://github.com/michelesalvador/FamilyGem/issues/104
2) have an option to select two persons and have the app show a) the shortest path between both (by bloodline ) and b) show all paths connecting them
3) allow selecting two individuals and display what their relationship / kinship is. Eg great grand cousin twice removed