Post completion OPT maximum number of working hours per week?

I concur with my colleagues, no cap except applicable state laws.

What forms to fill in to apply for a US Visa / greencard if you have resided with your spouse outside of the US for many years?

Your US citizen spouse should file I-130 for each of you. Item six does not apply.

Does the GC consular processing allow the beneficiary come and go on B1 while waiting for a consular interview or decision?

No it does not assure admission nor issuance of a B1. It may help convince CBP or the consulate of non immigrant intent, but it remains likely that...

C 19 is what you should include as my colleagues have indicated

Confused between c(19) and a(12) under eligibility category ( ) ( )i am a Haitian National and need to file TPS ASAP. Thanks

C 19 is what you should include as my colleagues have indicated

I need to go for H1b stamp Was given citation for property damage. Case is dismissed & expunged.Should I mention that in DS-160

It is better to disclose than not to disclose. Be prepared to present certified copies of decision., not expungement.

U visas 2016

10000 are authorized for the fiscal year. I you are not within the 10000 you will have to wait at least another year.

Can I quit my current job and wait for H1B transfer to be approved? I got EAD through the 1485 that my spouse filed.

Yes with the understanding that if the I485 is not approved you do not have status.

F1 Visa Change of Status- Starting classes before COS approved

As my colleagues have noted speak with your school's DSO,

Can I use my old H1B petition (2005)

Not likely although you should explore with your employers immigration attorney.