Getting married while (both) I-485's are pending and add derivative?

[Evils]

My situation is a bit obscure, so I'll try to explain:

Myself
H-1B (valid until Aug 2020)
EB-3 Green Card Application
I-140 pending for 205 days (No Premium Processing, no SR response)
I-485, I-485J, I-131and I-765 filed 57days ago (sitting with NBC)

Fiancé
E-2 Visa
EB-3 Green Card Application
I-140, I-485, I-485J, I-131and I-765 filed 30 days ago (Texas Service Center)
EAD, AP already received and I-140 approved (premium processing)


The reason I'm searching for help here is that my employer decided to outsource my department and due to some personal spite I'm being pushed out now. I might be able to stay past the 180 days of my I-485 pending to get AC21 portability, but that's not guaranteed and seems to come with it's own burdens.

1. Given that my fiancé is also in the Green Card application process and her job seems safe, what are the options for us?
2. What would be the process to become the derivative to her application and would that give me an EAD so I can seek employment without my H-1B (Timeline?)?
3. If I stay past 180 days and go the AC21 route, what would any future employer have to do to get to my GreenCard with this application?

Appreciate all the help!

[newacct]

2. You would file another I-485 to adjust as her derivative. You can apply for EAD and AP together with that I-485.
3. They would need to complete I-485 supplement J

[Evils]

Thank you!

Small follow up question (opinion/experience based). How much of an issue would it be during my GC interview if I would have left at 180days my initial employer?