Joint PR application (non-EEA spouse and 1 year old)

I’m from Poland and will be applying for PR with my Non-EEA spouse and one year old son which has Polish passport.
Is it enough if I provide only the UK birth certificate as evidence for my son?

I’m employed part time for the last year (after I came back from maternity leave)as I need to take care of my Little One and working 14-20 hours a week.I have worked full time for the same employer before I had a baby.
Is that enough for me to get the PR where I include my two family members?
Do I need to provide my husband’s details of full time employment to make our application stronger?
Is the covering letter necessary to explain pur situation?

Has your non-EEA citizen spouse completed five years of residence as your spouse in the UK?

By definition, your one-year old child does not have PR as he has not lived in the UK for five continuous years as your dependent. He should get a Residence Certificate, not a DCPR.

Yes,my spouse has completed 5 years together with me.
I would like to apply as a qualified person and was going to add 2 family members to the PR application.
I am only confused as some people say that I should only apply with my spouse for PR and when we get it we should apply for British Citizenship for our son(MN1)
The other thing is if we do not get PR for him or go MN1 route,could we just wait for “settled status” application after Brexit?
So many options,I am really not sure what is the best route.