Can I leave USA and come back after having dismissed domestic violence case?

You could but be prepared for secondary inspection and carry with you certificate of disposition of your DV case.

Will Spouse’s I-485 be impacted (delayed/rejected) due to job change of Primary Applicant?

As long as you are not impacted so is not your spouse.

I 130 still waiting.

I 130 takes many month before it is adjudicated. Waiting is the suggestion. Waiting patiently.

While getting H-1B Visa re-stamped for the new employer at the US Consulate in New Delhi, can be there be any problem?

That depends on the whole host of issues we know nothing about until we are familiar with your record.

I485 greencard application help ?

I agree. You can engage any immigration attorney you want by contacting the person directly. Run the search here and identify attorneys you would...

From outside the USA? Could be possible indeed.

From the day I -130 is filed not from the priority date.

What are the options for bringing my Canadian mother to the USA?

Petitioning for your immigration to the USA. You can do that as a US citizen.

How can I get invoice Id number for pay visa fee for my brother?

Is your brother's priority date current already to start being concerned about the invoice?

Is it also needed to attach a cover letter to DUI documents when applying for work permit under C8?

Did you read the instructions to USCIS form I 765? Do they instruct you to do that?