Checked luggage - same treatment on both. As OWS you get a second checked luggage for free (I think for the OWS member only, not everyone on the same booking)

The "premium" eco seats are for money even for AY's own Golds (=OWS)

I haven't looked int the earning chart of AA, but they go by fare bucket (ie. letters) so you'd need to check the earnings for each specific option.

I'd take (not spend) the $400.