My thoughts are probably going to be different than most here.
You are looking for some kind of list of what a WS should be doing.
I didn't give my H any list. After D-day#2, I planned to file for a D immediately and had even called a lawyer. But he talked me into giving him a chance to prove he could be a man who deserved me for his wife. It was early December so I decided giving him until after the 1st of the year would be okay. I was curious as to what he'd do but expected him to fail and expected to be filing in early 2007.
But he surpassed my expectations by far and here we are closer than ever as we are about to enter 2020.
For me the key was true remorse, which led him to do many things to show me how sorry he was, and that he truly would be transparent and faithful for the rest of our lives. And he has made good on that!
But I have read many "requirements" on this forum all through the years and I think, wow, most would tell me to dump my H. For example, he'd never join a forum like this, never read books on the topic. He did agree to MC but I certainly was not going to have him set it up. I can't see him doing that unless I hovered over him forcing it, which he would have done, but why would that be easier than doing myself? Anyway, I did it myself but cancelled because it took them 2 months to get us an appointment and by then we were well on our way and it seemed it would be a waste of time and money. He never did any IC or anything like that.
Oh, and the biggy, most of his answers to my questions were "don't know or can't remember." But I know him so well and his memory is horrible. It was a big hurdle for me because I did want to know details such as what they talked about. In the end I had to make a choice though, did I want to accept him as he is, or get a D? Changing him was not an option. I made the decision to forgive, but there has always been the clause there would be NO hesitation if he cheated again, or even established contact with her, I'd divorce him immediately.
As for serial cheater, I would never label someone as that based on they cheated on two wives. (Maybe yours is but I don't know what details you are basing that on based on what you said in your initial post). I guess my definition would be more complicated. My current H cheated on me (wife #3) and his first wife with the SAME woman. As far as I know he never cheated on wife#2.
Now my XH cheated on me more times than he could hope to count, and with ONS, prostitutes and at least 2 EA/PAs, and married the final AP. Yes, I would definitely label him as a serial cheater. Took him about 24 years but he finally also left wife #2 for yet another.
So what I am moving toward is you have to decide what YOU NEED, not what he needs, or even what he needs to do. He is who he is and he "believes he is doing so much" and you believe he is doing the bare minimum. You are probably not going to change him by telling him others agree he is doing the minimum. So my first suggestion is to look at what YOU WANT. The past cannot be undone. Is it forgivable? Many things you wrote would border on unforgivable to me, such as taking 10 days to "say goodbye." What a load of crap. Who cares about the suicidal homewrecker? Oh, yeah he did. And that goes on the list of negatives in my view.
My H showed no signs of caring anything about what happened to OW after D-day and for me that was a plus. I will admit we'd likely not be together now if he'd have still been seeing and pining after her after he begged me for another chance.
But I'm sure you and I have a different set of negative things we can or won't tolerate. Just something to think about as I am not advocating for either R or D. I divorced my first H and have no regrets. I R'd with my current H and have no regrets.
As for the 180, I'm not a huge fan of that for situations like you described. I would only recommend it for those who are feeling desperate to stay married to someone who is actively still cheating, or treating them horribly blaming the BS for everything that happened, for example. You do not sound desperate so I think increased communication would be a better solution than the 180 which would in effect decrease communication.
Good luck whatever you do, going forward.