That is one thing I'm not sure about, but I'm fairly certain that paying users don't have to buy extra from the shop to pay those. I think those certificates are gotten when you don't want to sub but want to keep your house, but I'm not sure because it wasn't the same in Russian version.
When you get enough crime points you get outcasted as a pirate (you need to get quite some). Pirate doesn't belong to West or East, but the Pirate faction, which has their own island with their own NPCs (because the main NPCs on land stop interacting with you). If you go over 50 points in crime when you die you get sent to court to be jugded. If you're found guilty you get thrown into prison for X minutes.
I found the Trial chat pretty hilarious in EU beta and some people have been sentenced for A LOT of time
For example (check bottom left for chat):
I think the trial system does have it's place in this game. But you can be damn sure if your wild farm gets discovered it won't be there when you come back. One thing to do about this is to set timers so that you log in to check the farm right as plants are ripe for harvesting, unless someone uproots them before they become ripe - which is one of the most vicious things you can do in ArcheAge, considering it's just causing grief (you and him get nothing if he uproots your shit).
I've also seen defendants buy off the jury (jury is always real players), so they vote him innocent
If you die in the safezone with your pack on back, I think it remains there for like 8 hours or so and then anyone can pick it up. If you die with a pack in the pvp zone or open seas, then they can pick it up immediately.