I don't know much about this visa.
This on the Cambridge University site, seems to answer both of these questions.
"Until a student receives unconditional approval for their degree from the Board of Graduate Studies, standard Tier 4 conditions apply (e.g. your work hours are limited);
The less restrictive terms of the Tier 4 Doctorate Extension visa apply from the date on which the PhD is completed (if a valid visa application has been made before this date), even if the applicant is still awaiting the outcome of their visa application;"
https://www.internationalstudents.cam.ac.uk/immigration/work-visas-after-study/doctorate-extension-scheme
It would be best if you asked the Internationl Advisor at your university as they will be your sponsor and will answer your questions.
For the spouse visa (whatever it is called) ask ksand.
My PhD is due to be completed on the 15th of this month and awarded on the 1st of August, but then I graduate on the 12th of July. It's all a mess. But I know they said my DES visa will likely run out August 1, 2018.
I will ask my advisor as I have to go to the school to make the application anyway. That might be the answer.
Sorry to have such a weird, complicated question.
I just want to know what we have to do. Nothing is impossible and it doesn't mean I can't stay if the self-employment route doesn't work, I just have to know what route we have to take.