I am also struggling with many of your questions in my own situation. This is where I am on some of them.
Is the change real?
I don't know, but I am watching and waiting. 4 months out and I consistently see him trying and working. It's enough for me to " not divorce him" but not ready to say Reconcile.
We never physically separated.
Is he likely to cheat again?
I think yes - but, if he works hard to change, can that be offset? I think yes on that, too.
This is the second go- round for us BUT the first time we both rugswept. It is completely different now. Both in IC, MC, hubby is giving me what I ask for and even things I didn't ask for that he is being proactive about. I can say that the only reason I did not leave after Dday 2 is b/c we rugs wept the first one and I wanted to be able to tell my children I did everything I could if we did end up divorced.
If the A was not a deal breaker for you, and you feel a possibility in your heart for the 2 of you, there is nothing wrong with leaving that door cracked open BUT making sure there is consistent proof of change over time to make you feel safe enough to move forward before you go all in. In other words, reserve the right to walk away, set your boundaries and stick to them.
If he moves back home, does this excuse his past emotional abuse and cheating?
NO. The decision to end the separation is yours, you must feel safe first of all from any abuse. There is never an excuse for that behavior. I don't know what I would do in your shoes, you would have to use your own judgement. I can say that if you have a remorseful WH who is trying, and you want to give things a chance, then I think it would be much harder to be physically separated. Living together for me means still having a second parent there,not wondering so much about where he is/ what he's doing, and being able to take the opportunity for discussions when they come up. And yes, it has provided opportunities for mutual comfort and closeness.
Is an in- house separation possible for you? It might feel less risky if you could preserve some distance, but still be a step towards letting him show you his consistency.
I am such a newbie myself, here, maybe I am way off base. Your story speaks to me, and I have been following your posts. I think you are amazingly strong to do all you have done, and with a new baby too. Whatever direction you choose, and it IS your choice, I feel you will make it through even stronger. I wish you the best.