Do i need a lawyer?

You should definitely consult with an attorney experienced in VA matters.

I am appealing a Field Grade article 15 by my Battalion Commander does my appeal have a chance?

Without knowing all the facts no one can gauge the chances of success.

Does active duty service member stationed in Germany need to be physically present for trial?

This is not a Military law issue. However, his attorney, who is much more familiar with the case than any of us, is the best source of information.

Unless it was a purely administrative mistake (like a typo) on your DD 214, your discharge cannot be downgraded.

If the United States Military discharges a person based on a mis-diagnosis, can that individual sue for reinstatement?

The first step is a petition to the Board for Correction of Military Records. If that fails, then one can sue for reinstatement. But military...

Did my background investigator failed to do her job correctly? (was advised by other NYPD officers that i need to sue)

This doesn't sound like a violation of the law but check with local counsel to confirm.

Got hurt in military boot camp, did not finish. Am I entitled to a military pension?

No, but you may wish to contact the VA.

What must I file for military discharge upgrade when you have exhausted all appeals through the service and the discharge board?

You must file suit in either Federal District Court or the Federal Court of Claims, depending on the relief you seek and several other factors. If...

Do I have to respond to Interrogatories and Request of Admissions if I object to them?

Hopefully you are represented by counsel who will guide you through the process.

Cry for help!

There are many fine Nevada lawyers here on AVVO or you can call the bar association's lawyer referral service.