Answer to 1, 2 and 3:
Yes you can modify your application at anytime provided your eligible for the pool. If you’re not then you have to reapply.
Candidates are picked from the pool every time they do a draw (the time schedule is up to them). Your application can stay in the pool for up to a year.
Keep in mind if you’re wife has a higher degree and more work experience it might be beneficial to make her the principal applicant.
Answer to 4:
Not really if your score is above the cut off during the draw you’re invited. So if you potentially miss the cut off for the first draw then add your wife’s details and make the cut off on the next draw you are not really delayed.
Answer to 5:
Primary is enough. Depends can come with the primary o after but not before.
Answer to 6:
Each of your family members on the application get their own PR card if they cannot live in Canada for at least 2 out of 5 year they will loose their PR. For citizenship you have to live 3 out of 5 in Canada.