I'm not on T yet but I know there's a lot of info out there. The internet is brimming with the stuff

In
Elwood's thread, the conversation sorta steered toward T, so maybe you can check it out. There's also videos of people on T on youtube, from first day on T to 5 months on T (etc) so you can see and hear the actual physical changes.
From what I've heard it's better to have the hysterectomy before beginning T but your son doesn't have to, it's all trial by trial and everyone's case is different. Basically the process of taking T is going to pretty much work toward eliminating all the estrogen in his body and having a sort of menopausal phase for a couple of weeks before his monthly visitor stops altogether. Without the hysterectomy, he's going to have to take T the rest of his life or the estrogen will start to produce again a while after stopping T and yeah, the physical changes will come too. Um, I think you were looking for general info on it as far as I can tell so I hope that helped. It's all speculation on what I
think I remember from things I've read though so make sure you check it out yourself too.