1. At the start of your next turn, like a returning weapon.
The hurl spell was originally printed in 3.0, specifically in Dragon Magazine #275 back when WotC was running the magazine. Really early stuff, that. Back in 3.0, they used "your action" as verbiage for "your turn." This is also why standard actions were "partial actions" back then. Over time they stopped using this language because it is, frankly, deeply confusing in a game with a bunch of different other things called "[noun] actions."
Nonetheless, the argument that it brings it back at the start of the next action you take, rather than the next turn you take, isn't strictly RAW. It's also not strictly RAW. It's ambiguous, since while they did not update the wording for 3.5 when they ported hurl from Dr275 to the Spell Compendium, they also didn't unambiguously excise this type of wording from 3.5 in the 3.5 update back in 2003.
We can see vestiges of it in stuff like the Dodge feat:
During your action, you designate an opponent and receive a +1 dodge bonus to Armor Class against attacks from that opponent. You can select a new opponent on any action.
The Combat Expertise feat:
When you use the attack action or the full attack action in melee, you can take a penalty of as much as -5 on your attack roll and add the same number (+5 or less) as a dodge bonus to your Armor Class. This number may not exceed your base attack bonus. The changes to attack rolls and Armor Class last until your next action.
The Stunning Fist feat:
You must declare that you are using this feat before you make your attack roll (thus, a failed attack roll ruins the attempt). Stunning Fist forces a foe damaged by your unarmed attack to make a Fortitude saving throw (DC 10 + ½ your character level + your Wis modifier), in addition to dealing damage normally. A defender who fails this saving throw is stunned for 1 round (until just before your next action).
And, in a phenomenal way to illustrate why this wording fell out of favor, in the delaying and readied action rules:
Initiative Consequences of Delaying
Your initiative result becomes the count on which you took the delayed action. If you come to your next action and have not yet performed an action, you don’t get to take a delayed action (though you can delay again).
If you take a delayed action in the next round, before your regular turn comes up, your initiative count rises to that new point in the order of battle, and you do not get your regular action that round.
Anyway, throwers need to be thrown (heh) a bone, they're awkward and janky in 3.5. Nonetheless, the spell's wording does not strictly imply that it would return at any point before your next turn; if you take the "your next action" language to mean "any action you take" it makes hurl a lot better, but also breaks other things in the system if you're to apply that ruling with any consistency. It's absolutely a valid houserule to apply here, but at that point I'd probably just make all stuff that works like returning cause the weapons to return instantly, just to make life easier for thrown weapon builds.
2. Like a returning weapon, there's no limit to the distance.
This is because like many super early-3.0 things, they really just didn't think that element through.