The Future Lies in the Past, part five: MoM, Can I Borrow the Time-Turner?

I want to start this post out with an excerpt from MuggleNet/Leaky Cauldron's interview with JKR:
MA: Here at the end you sort of get the feeling that we know what Harry's setting out to do, but can this really be the entire throughline of the rest of the story?
JKR: It's not all of it. Obviously it's not all of it, but still, that is the way to kill Voldemort. That's not to say it won't be extremely an torturous and winding journey, but that's what he's got to do. Harry now knows - well he believe he knows - what he's facing. Dumbledore's guesses are never very far wide of the mark. I don't want to give too much away here, but Dumbledore says, "There are four out there, you've got to get rid of four, and then you go for Voldemort." So that's where he is, and that's what he's got to do.
ES: It's a tall order.
JKR: It's a huge order. But Dumbledore has given him some pretty valuable clues and Harry, also, in the course of previous six books has amassed more knowledge than he realizes. That's all I am going to say.
ES: It seems like it would be impossible. If Harry had gone to the cave, he never could have done it on his own, it seems like.
JKR: Well, I'm prepared to bet you now, that at least before the week is out, at least one of the Horcruxes will have been correctly identified by careful re-readers of the books.
Ooh.... Well, there's the locket he saw at #12 Grimmauld Place, the wand on the purple pillow at Ollivanders, the Hufflepuff cup...somewhere. Other sleuths have asked about that tiara Harry saw in the RoR in HBP.... Others think Harry (or his scar) is a horcrux, but I wish to avoid that argument...for now. Still others consider the possibility that the (now cursed) opal necklace once belonged to Rowena Ravenclaw...another topic lacking proper canon (though opals would be perfect for any Ravenclaw, what with opals having to do with sight and the unused powers of the mind...but that's perhaps for a later discussion)....

JKR is suggesting the locket found at #12 Grimmauld Place, since she mentions horcruxes right after the question about Harry in the cave, but is that horcrux aready destroyed by the time we see it in OotP? I think so. However, Harry still has to find it and make sure it's no longer a viable horcrux.

JKR says the journey is going to be "torturous and winding". This suggests Harry has a lot to do in a "short" amount of time, and how do we give him more time? By letting him go back in time.

How will he go back in time? I see four options, so far:
1] He gets hold of a time-turner that wasn't destroyed,
2] Ron's new watch might have time-travelling abilities,
3] Harry might inherit Dumbledore's watch, which might be capable of time-travel, or
4] The Room of Requirement (or "Come and Go Room") might be able to send Harry back in time.

I'll have to add to this later, but I might put it in a new post...we'll see.

So. It's a tall...no, huge order. And Dumbledore has given Harry "some pretty valuable clues".

Anyone else think that Harry will use the Room of Requirement, or "come and go room", in order to travel back in time directly, or that he could use the RoR to supply him with anything he'd need for the trip? In OofP, Harry's DA practice room seems to have taken or copied Moody's Foe Glass. Why couldn't the room supply Harry with a working time-turner or some other time travel device?

There's also the chance Harry could "smuggle" a time-turner out of the MoM. Not only does he have supporters working there, but he was able to access the DoM back in his 5th year at Hogwarts. It would be silly to assume that all of the time-turners broke that night.

Third way to get a time-turner: borrow one from a supporter who has had one in possession since before the raid at the DoM....