Nowhere does it say what fps setting the timeline is using. I presume it's 30 fps but there is no visual clue to that.

Also, what happens when I export to AE in 25fps, is the animation translated from 30 fps to 25 fps and how is it done?

It would be much better to animate in the fps you are going for in the end as there can be weird translation errors between 30 fps and 25.