[Bernardo Pantoja]

If I read your description correct, have you tried exporting each scene as a clip then sewing those clips together in a new timeline? It would be less taxing on Premiere.

All the best

[Bernardo Pantoja]

I believe you want to click the triangle next to property you want to animante. Then click the zoom in/out buttons on the bottom of the effects control panel. They should look like small/large mountains.
I hope this helps.

All the best