That is a really interesting set of questions, but sadly, my reply would have to invoke the dreadful "that depends on the specific country and time and situation" and then I would have to go and explain various possibilities which would probably bore everyone to death.
But in most broad strokes:
>How well-known is the law?
Generally speaking, customs are known, but knowledge of law (if there is any) is restricted to very small portion of the population: nobles, judges, bureaucrats, priests or who ever has the supreme authority in that particular society.
>Are all people equal to the law?
NOPE. Not even the slightest. Not even remotely. My god no. Even the most egalitarian societies in my world would consider at least men and women completely different cases and subjects of law.
Most would consider consider differences in standing between slaves, serfs, free men, nobles, men and women, and any other possible rank on whatever local social hierarchy exists absolutely insurmountable.
>What authority are they handed over to?
Elders of the community in most cases, local lord and his posy in most others, local judge in the rest.
>How is the trial set about?
That would vary from simple hearing in front of the authority, to massive gathering of multiple tribes and their families and collective negotiations.
>Is there a jury?
Not in the english-american law sense, no.
>Would there be some state/temple appointed defense lawyer
No, never. In some societies, it's possible to hire a representative for your case, but nobody will bother giving you one if you can't afford one yourself.
>what is prison like?
No prisons. People get thrown into dungeons at times, but mostly things are solved by: confiscation of weath, public shaming, beating, branding, slavery, maiming, exile, torture, execution.
Nobody ain't got time and money spare to feed mass people in isolation for years just sitting pretty: Criminals are punished, not isolated.