Ok so whether you are accelerating or decelerating, you need to know at what speed you can extend or retract one more stage.
If you are accelerating, those speeds are F speed (to conf1) and S speed (to conf0).
If you are decelerating, those speeds are the amber = marks which move down every time you select a new conf.
So to answer your questions...
1. Yes, Athr will maintain F/S/O speed for you, so long as it is engaged, and the approach mode is activated on the fmgs.
O speed (green dot) in Conf0
S speed in conf1
F speed in conf2/3
Approach speed in conf full (Or conf3 if that is landing configuration)
2. Yes of course you have Vfe. It is Vmax, the top red band on the speed tape. Vmax=lowest of Mmo, Vmo, Vle, Vfe.
So you have three speeds relating to the flaps configuration...
1) Vmax, which is your maximum speed for the configuration (=Vfe on approach)
2) amber "=" which is what the Vfe will be if you select one more stage of flaps
3) F/S speed which is the min speed before you can safely retract one stage. (Think of it as roughly where the new Vls is going to be after selecting one stage up)