Exactly - a GJ looks at the evidence presented and has to decide basically, "is there any possible way a reasonable and fair jury could find this person guilty" - and if they think yes, there's an indictment.
Usually this is just used to weed out really unfair/bias charges - like the only evidence was a black man in a white neighborhood. Clearly not enough for a charge.
But in a GJ there are no evidence rules either - so hearsay is admissible, so all of those things her friends said can be admitted without corroboration... so the jury will hear about her pasta cooking from TL, her dislike of Cindy, etc.
JB definitely knew because I bet CA, GA, and LA are subpoenaed. Tim Miller probably too - they have to give you enough time to get down there, so he was probably being a GREAT citizen and just saying he was coming back rather than he had to come back to testify.
GJ are in secret - you'll never find out who the jurors were, and they'll never release the witness list. Sometimes it goes as far as random times of day or night if its a super sensitive case, b/c some witnesses could be afraid to testify - and since the accused is not locked up yet, theres a huge danger to talking witnesses.
But yeah whoever said a GJ will indict a ham sandwich - cooooorrrect! :dance::dance::dance::dance: