Question about users vs cck
Do these people need to login to the website? Do they have to change those profile settings themselves? do you plan that those entities will interact on that page? If any of these is yes, than you probably want users.

In all other cases this is probably a no and you are good to go with content types/ custom entities.

for keeping a record of past positions, you might want to try out field collections, you could create a field collection with start, end, position for instance and allow n entries of it.