contact the consulate in London to see if they make these accomodations

What US visa i would need? if i want to start a new company?

I would set up a consultation with a qualified immigration attorney to discuss the L visa.

H1B Petition at the port of entry

Talk to the immigration attorney for you company who should and can fill you in on what is needed at entry.

What are the documents required to re-enter the united states after a stay of less that 6 months in a foreign country?

A valid passport and valid green card would be needed. That is all. If she has trips more than 6 months or more than a year, I would look at...

Review the first column in link and figure out what filing type you fit in to find the address that it needs to be mailed to.

One should be truthful when completing the DS-260. Simple as that.

I am a PhD international student and i have applied for OPT but i may not finish my dissertation can i work off campus as ABD

Please talk to your DSO. That would be the best start here.

I-130 Petition for Parents

You can provide an explanation regarding the discrepancy. I would suggest maybe hiring an immigration attorney who can help respond to the RFE to...

N400 delay (10 months and counting)

Start with setting up an infopass appointment. If you still see no movement you may need to consider hiring an immigration attorney to pursue...

Can I change schools before paying tuition (F1 student/ change of status)

You can try to get a 2nd I20 but whether it is successful is another matter.