If it went to trial, we *would* know all the facts.
No, no you wouldn't. You would only know what the prosecution and defense could find and present. Nothing more, nothing less.
As it so happens, the DA promised to release all the evidence they have to the public shortly. When, how, and in what format I do not know, but nonetheless, that's what they intend to do according to their statement.
A grand jury doesn't determine guilt or innocence, it only decides whether a trial should happen.
Agreed. The reason for having one in the first place is to determine whether there is enough credible evidence and testimony to be worth a trial.