Immigration. What does this mean?

The application you filed has been transferred to the Boston USCIS office for a decision.

How much yearly income am I require to proof that I can support my GF and two kids and get their green cards.?

This depends on the number of dependents and any other people you may have sponsored in the past. Visit www.uscis.gov to review the I-864...

If my visa is denied, will this be a problem when I try to visit the United States?

There can always be a problem if a CBP officer believes you are an intending immigrant arriving as a visitor.

I have an INFO PASS appointment for September 2,2014 @8:45AM to get temporary evidence of my immigration status.

Yes, you can bring copies of whatever you have to the InfoPass appointment.

Change non-immigrant visa status from tourist/visitor visa to Q-1 exchange visitor visa

There are no guarantees in any immigration applications, much like the rest of life.

N400

If the USCIS is seeking your denaturalization, you should consult with an experienced immigration attorney immediately.

Can I work legally from another client facility located in suburb with an approved LCA for one client location?

This may depend on whether the new location is in a different MSA, but in any case, you should discuss this with the company immigration lawyer.

On 21st August my EAD status changed to "Document Production." How long does it take before they mail the card?

It usually arrives within two weeks of that indication on the website.

I-130 and I-29F

The problem is that if the I-130 is approved, the State Department will not issue the K-3 visa, so your wife would not arrive here faster and you...

You may be able to have any required "corrections" made at an appointment with the CBP. Consult with an immigration attorney for specific advice.