I don't post much anymore here about my situation, but still read and follow others religiously. You HaWho are doing a fantastic job! My BD was right around the same time as your first one, but my H left shortly thereafter...then filed for divorce in late 2015. We are still not divorced!
I was not a good DBer in terms of my saving my marriage. I begged, tried to reason with him ad nauseum and spied on him way way too much the first few years. But the one thing I think I did right was take my time. He wanted the divorce and wanted to rush it. I didn't, so I took my time. You seem to already know this, but please don't agree to anything you don't want out of confusion or fear. The entire divorce process is exhausting.
I was served through certified mail (not sure if it's different in your area) but your H threatening embarrassment through being served seems to me to be a scare tactic.
My H threatened court for custody issues...but I kept waiting and pushing, not agreeing, but countering and we finally ended up with an agreement I can live with without court.
It seems like you have already done some homework, so my only advice is don't listen to your H and act on your own timeline. In my experience nothing happens quickly in the legal system without mutual consent.
FYI...I also got the line "we should use the same lawyer...it'll be cheaper and quicker". I think that's standard script. We both have our own lawyers now. It's not cheaper, but I feel much safer for me and my kids.
M: Early 40s H: late 30s 2 kids under 10 M: 15 yrs BD: 7/14 S: 10/14