The dates are not my biggest concern, I can easily export them from Filemaker as three fields (dd, mm and yyyy) and use php to calculate the 'years ago'.
Exporting to csv and importing into ProcessWire also works like a charm, I already tested with the 4000 names.
I understand that this needs careful planning. It's a bit confusing to decide what should be main categories with parent and child pages. I have the impression you can go on in dividing data almost endless. A major doubt right now is to decide if 'events' should be categorised by date (parent=month -> child=1,2,3,.... -> child=event1959a, event1959b, event1969a, event1983a,....) or by event (parent=event -> child=birth, fact, death -> child=event). In the last case it's possible to keep categorising forever. For instance deaths can be split up in say cause, suicide and murder. Then again cause can be split up in heart attack, stroke,.... But in the end they should all show up in pages listing events resulting from user searches like "what happened on my birthday?", "which musicians were born in my hometown?" or "who was murdered by an axe in Belgium?".