Dependemt Visa Application for new born

I am on Tier 2 General visa (From Jul-2020) and I am applying in-country for a dependent visa of my newborn in the UK. I have a few queries which I have listed below. Would anyone be able to help with the below queries please?

1. After registering the email, I received an email for verification that states "PBS, Start-up, Innovator or Global Talent dependant child" - Is this the correct category as I am on Tier 2 General visa?

2. Once I enter all my details including my DoB, Passport & BRP and COS details, I am getting the form for entering the details of my child.
2a. How long have you lived in the UK? - Is this the during between the child's DOB till date?
2b. Have you been to the UK in the past 10 years? - Do I select No for this question since the child was born in the UK?

3. Finally in the declaration section, below are the options
A. I am the applicant aged 18 or over
B. I am the applicant aged under 18
C. I am the parent or legal guardian of the applicant who is aged under 18 and completing and submitting the form on their behalf
D. I am submitting the form on behalf of the applicant
3a. When I select option C, I am getting the question "In what capacity are you representing the applicant(s)?" When I select "Family Member" option as I am applying on behalf of my child, there is a question "How are you related to Mrs XXX?" - I enter the answer as Mother and in the next page it asks for "3rd party declaration - your details" which ask for providing 3rd party details including Name, email ID, Address - Shall I add my details here or my child's details?