GIS system prototype

Hi!

I would like to create prototype or so called minimum viability product of a GIS system with just a few custom features. Basically, I should be able to upload different models of a same building with regards to how a building look like in different time period. As a user, I want to have a timeline which I could use to see how this building evolved in a time.

Questions for potential MVP features consideration:
1, In case of using more buildings or a whole cities, are we able to create an online version of such system (i.e. google earth with such timeline) or we should have offline version too?
2, Are there in such GIS system possibilities that models will be edited by 3rd parties (update model colour or a shape i.e.) or is that something typically not used in GIS systems?
3, Is there any integration that would allow users to "zoom-in" our models into a 1st person view typically known from a computer games?
4, Regarding point 3, is there any integration that could turn model into something closer to computer game where users could just see silhouettes to moving in your model city ( i.e. 10 moving objects in a shape of a persons).