I would hold off on the carrots. They really aren't a great food item for igs. Some people have found a fruit that igs like...bananas for instance...and smeared that onto the greens to encourage them to eat. Fresh greens are better than pelleted food, but it can be a slow process switching them over to a proper diet if they prefer something else. Usually it involves feeding the preferred diet (unless it is something harmful like spinach or iceberg). Hold out and the iguana will get hungry enough to eat. If she's hiding and not getting as warm as she should, this will slow her metabolism and decrease her appetite.
Here's what I would do if it were my ig...your mileage may vary. 
First, I would offer a fresh salad every day comprised of 50% dark leafy greens (collards, dandelions, mustards, escarole, with occasional kale, bok choy, endive) and 50% vegetables (raw green beans, snap peas, snow peas, squash, sweet potatoes, and occasionally carrots and parsnips). I would top it off with a small quantity of colorful fruits (apple, mango, papaya, plum, strawberry, blueberry, and occasionally grapes and banana). I have a lot of these foods around either because I eat them or I feed them to my beardies and tegus. I wouldn't make a large salad until she was eating readily and that way you're not wasting so much. I would also provide a small sample of the pelleted food to make sure she is eating something, but I would also begin decreasing it with the idea of removing it from the diet except for occasional use.
Hmm...the hide box is an interesting issue. You've only had her for 3 days or so, so I'm sure she's stressed. I would keep her in an area where she sees people and by a window where she can see the world, but not in the main traffic area where she's overwhelmed. Give her another week and she is if she starts to come out more. In the meantime, make sure the hide box is on the warm side of the cage so she is at a proper temp for digestion and overall health. Does she have any health issues? I have a 10yo beardie who likes his hide a little too much. When I noticed some decrease in appetite and face changes, I took away his hide for a time, forcing him to bask in UV. I don't think your situation is that drastic, but maybe you could put her outside for a time in basking cage.
Lastly, I would also bathe her every day in a lukewarm bath for 15-20 min to rehydrate her and keep her skin in good health.
The stool sounds like it was just some urates and liquid. You can get a fecal check done for parasites and give her some Nutribac probiotics for good digestive health.
There's another great message board at the green iguana society. Sorry, I don't have a link.
