Is it possible to edit every detail of an Illustrator file in After Effects?

The closest you can come to that is to install Adobe XD, open XD, create a New XD file, use File/Import to add an Illustrator file, and then, before doing anything else, select File/Export/After Effects from the menu. After Effects will open and load a new comp full of shape layers from your Illustrator file.

Every element in the Illustrator file will be a layer or a nested comp. You can do as much editing as you can on a shape layer. If the AI file is complex, you can end up with a huge comp filled with nested comps (pre-comps), and it can get very confusing to edit. You cannot make all of the edits you can in Illustrator because Shape Layer editing is limited to shape layer tools, but this is as close as it comes to editing all elements of an Illustrator file (fileName.ai) in After Effects.

No, of course not. In order to even "edit" an AI file you have to convert it to shape layers and masks and then there are limitations and a lot of stuff isn't supported. It would be a much better strategy to actually think beforehand what can be created natively in AE instead of endlessly wasting time in AI and finessing stuff that won't carry over to AE.

Mylenium