SamiSami

Not for the petitioner.  Only for you.

NO, even if he is Filipino.  It would not hurt to get it if he's Filipino though.
 

An I-797c is just a notice of action.  Is this a receipt notice or an approval notice?

Absolutely correct.  However, it would be helpful to know WHY or for what purpose they need a DNA sample.  Is this about a child?  What?

Note that an employed person does not qualify based on tax return information.  You qualify or not based on "current income" which comes from a "pay stub".

And when you see a post in a spouse visa forum, it's prudent to interpret AOS to be Affidavit of Support.  Pay attention.

If you already have his 2018 tax return documents, then Line 6 from 2018 1040 will go to Part 6 item 7. Part 6 item 20 is just the summation of item 7 to item 19. 
 
Line 6 frm 2018 1040 will also go in Part 6 item 24a.
Line 22 from 2017 and 2016 1040 will go to Part 6 item 24b and c.

Oh ok. I thought there was something newer that I was missing. I had read about T's proposal to raise it to 250%, and was afraid that that is what OP was referring to. I'm relieved. Thank you!

Dead wrong as to US immigration.  The rest doesn't matter.

It sounds like you are adjusting status from within the US.  If so, there will be no visa.  If you are IN the US and are STAYING in the US, yes, you apply for work authorization, not a "work visa".  Follow the Adjustment of status guide.  If you will be outside the US waiting for a visa, then NO, there is no work visa available.
 
Visas are used to ENTER countries.  If you are already here and staying, you will get no "visa".  Please clarify what you are trying to do.

It is not YOUR I-130.  The US Citizen files the I-130 on your behalf.

Thank you so much indeed . What about the house hold income and individual income please.