Please advise me on checklist for concurrent filing of I-130 + I-485 for mother on B2

[snow01]

I am a US citizen who wants to file for my mother who is in US on extension of B2 visa. Her extension of B2 is valid for another month. Please let me know if some documents are missing from my checklist.

I-130

I-130 Form
Check for Filing Fee
Copy of my Naturalization Certificate
Copy of my Birth Certificate


I-485

I-485 Form
Check for Filing fee + biometrics
Copy of beneficiary I-94 form
Copy of approval letter of extension of B2
Copy of beneficiary current passport (biographical page, visa and entry stamps)
Copy of beneficiary Non Availability of Birth Certificate
Two passport-style color Photos of beneficiary
Form G-325A, biographic information for beneficiary
Sealed envelope containing Form I-693, Report of Medical Examination and Vaccination Record
I-864 Affidavit of Support + Bank Statements, Pay Stubs, W2 for last three years.


I also have a few questions,

1. Do I need to apply for extension of B2 again for my mother while filing these forms?
2. Can my husband fill form I-864 as he's the one employed. We do have joint bank accounts.
3. Do I need to get the Police Clearence Certificate for my mother from her home country?
4. Should I consult an attorney to take my case or I got it all figured out?

Thank you for your time.