How to obtain necessary documents before the initial interview

You do not need the EAD, SS number nor advance parole before the interview.

Every case is different. This not out of the ordinary.

Applied for green card since August 2015 and USCIS telling me that my file is still in review.

Likely security check related. You can either continue as you are or confer with an immigration attorney about other option ie. mandamus

Talk with your attorney not the DA and have your attorney confer with an immigration attorney.

Change of status possibility from B2 to F1

As my colleague noted from eiter no possibility to approval, although approval is not likely especially if USCIS learns that there was a prior...

The case status hasn't updated after submitting the RFE response (H1B transfer in premium processing)

Have the petitioner or the petitioner's attorney contact the premium processing unit.

How to write a quality affidavit for uscis?

See instructions for I-864 or I-134, I-361, I-864EZ or other affidavit which is applicable to your filing

Review the instructions for C9 and if you fit the requirements for C9 than enter C9. Submit all requested evidence or expect to receive a request...

H1B portability during 60 day grace period

If you had been maintaining status and are eligible for addition time, probably be okay to begin employment. Before doing so speak with the...

Can I change an organisation?

Change of employer and location and extending good to confer with your immigration attorney beforehand and a filing should be made.