Can I travel to India and get an H4 through consular processing while change of status is pending?

Yes, you can abandon your COS and EAD applications. Write a letter to CIS ... then get a visa stamp.

Should I submit taxes or stubs docs with i751?

No need to duplicate your answers. Joint taxes would be good. Affidavits from friends/family/neighbors is essential.

Should I submit my pays stubs or taxes report with i751?

No need to duplicate your answers. Joint taxes would be good. Affidavits from friends/family/neighbors is essential.

Joint taxes would be good. Affidavits from friends/family/neighbors is essential.

How many yeats

He will have to wait for 6 to 22 years, depending on nationality. Most of the world is 6, Mexico is 22, the Philippines are 11.

Can I bring a different affidavit of support form as a backup to the visa interview?

Yes, you can bring an additional one. Or, you can contact the NVC and have them unlock your 864 ... then upload the new form/documents.

How long can immigration hold someone without the person being in their system?

More information is needed. Is this the first time he's had dealings with ICE/CIS?

CA proof of residency

Be patient, move slow. Wait for the plastic greencards to show up before thinking about CA IDs ... the mailer/envelope is additional proof of...

Removal Proceeding AFTER Adjustment of status was filed

Stick with your lawyer. Yes, filing the forms BEFORE the NTA is a good thing.

Can I use my parents’ income to meet income requirements when sponsoring a green card for them?

No, since it seems like your parents have been working 'illegally' .. their income can't be used. BUT, if they give you money to put into the...