for
1) it is fine to have the same dates or different dates
2) yes you need to print and write backside on the occasion.
3) it is fine as long as you guys described the same in the relationship document or chat document.
There is no dedicated answer, it varies depends on the PA applicant visa office and application itself, I know some people got in 4 months after their SA approval.
possibly yes.
detailed are described here https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/operational-bulletins-manuals/permanent-residence/non-economic-classes/family-class-decisions/admissibility.html
Better to resubmit soon, I got AOR, SA and medical, and biometrics all in the span of one month. People are getting AOR's in 3/4 weeks for Feb/March applicants.
You don't need to upload, the medical result will be sent by physician and may take a week or so based on where you give medical and turn around time.
For upfront medicals (like express entry) there will be option to upload e-medical letter.