for automatically putting a modifier on an object, it could simply use either the bounding box, or a box that perfectly boxes in the object. It doesn't have to get fancy. If people want the modifier to be different they could change it.
As for multiple modifiers. What I'm saying is that it wouldn't matter which went first. Basically, the modifier would work as it does now, but instead of choosing from 1 of the multiple options for what it does, you could choose multiple ones. Since anim8or uses a sort of bounding box for the modifier and when you change the modifier you can see the change you made on the bounding box, this same thing would happen with the multiple ones. Really I think the only thing anim8or would need to know is to do the 'bend' modifier last.