All 5 Princess Yue die at the same time, and thus trigger at the same time, but each trigger is added to the stack separately and resolve one at a time. In short, you'd end up milling 60 cards with the original Ruin Crab and the 5 land copies.

You're clones will always enter as copies of Agent of Treachery. What Rhadamanthus said is largely correct, however, if you choose to apply Infinite Reflection's replacement effect first, Clone will now be entering as Agent of Treachery and no longer have it's own ability, so that replacement effect no longer applies and you end up with Agent of Treachery. If you apply Clone's effect first, you'll then have to apply Infinite Reflection's ability as it's still relevant, and end up with Agent of Treachery.

Another thing to note about Restless Prairie is that it's attack works as long as it's a creature, regardless of whether it become one through earth bending or it's own ability. The same is true of the other 'Restless' lands from Lost Caverns of Ixalan and Wilds of Eldraine, but is not true of older lands, such as Raging Ravine from Worldwake, which gains it's triggered ability from it's activation. 'Restless' lands that have keywords (like Restless Anchorage having flying) is also tied to it's activation and don't function off of Earthbending.