Once you get the adventure you have 30 minutes to enter the zone, and once the first person in your group enters the zone you have 90 minutes to complete the adventure. If you've never done an ldon before, I would recommend a collect mission, where you are asked to go into the instance and collect a certain number of no drop items. These are the easiest ones imo, and the ones that people seem to do most often.
If you die in an ldon and do not get your corpse before the instance shuts down, it will pop outside the dungeon entrance about 30 minutes after the adventure ends.
Also, I'm pretty sure that an ldon adventure's difficulty is NOT dependent on the level of the person requesting the adventure. That is how OOW instances work. LDONS are based on the average group level, no matter who requests the adventure.
And as for xp in ldons, at lower lvls its pretty good. Once your start getting into your 40s and up it decreases dramatically compared to a good xp group in a regular zone. Most people do them either for fun or for a certain item, eg a lot of pet classes will be doing north ro adventures, as there is a pet focus item that can be bought there for 760 adventure points.
Have fun, they are certainly not as popular as they used to be, but they're still a great time.
EDIT: Dependent on what race you are, there is an npc in your hometown you need to talk to to get your adventure stone. Usually you get a message, but I also have not gotten one with one or two of my toons, not sure why. If you can't find info on the boards, I would just ask in general chat or something, someone should know. After you talk to npc in your home city you will need to go to one of the npcs in any adventure camp and hail him and answer his questions to recieve your Adventurer's Stone. The stone isn't required to do ldons, only to travel via the magus's. (pretty handy means of travel though)Also, you don't have to have the stone in inventory, as long as it's in the bank.
Edited, Tue Apr 4 01:26:35 2006 by darkstarr