[Heaven's Night]

I think that you can have both (but maybe after you finish changing). I've seen enough porn that you can tell it is possible.

I think crucially, you can't have both while you are trying to grow your breasts.

As a (bad?) analogy, it's like directing all your energy and resources to the breast growth construction project, and that diverts resources away from your male genitals.

No you can't, not really. Trans women who do porn typically have implants and they very often pop certain performance pills. But full on male function withHRT feminised body just doesn't quite work like that. Porn is all make believe for horny dudes to pour their money into. Its quite not that simple, there's always trickery involved in some way.

Of course, grow boobs, then stop hormone treatment to retain function can appear as if it works out but that would be counterproductive to the achieved body changes as a lot of it depends on hormonal upkeep. 

What comes to prog, its essential, but the reponse to it is individual based on genetics etc. Some people don't get much out it and others have breast volume balloon like crazy. But for full breast maturation, P4 is absolutely on the list of essentials right after estrogens.