Is the diet we have planned out for her going to be a good enough?
Yup, it looks great to me! The only things I can think to mention is to make sure you're only introducing one new food at a time, whether it's a cat food, veggie, fruit, baby food, etc. That's great that you're doing the baby food and meatball things! But just make sure you're introducing the parts of those one at a time too, so you can catch any allergic reactions and you don't upset her stomach.
Is 78 degrees an acceptable temp for her?
Yup, that's a good temp. Watch her for cues as well though, I know there's a few hedgies on here that actually do like it cooler, around 74-75. 78 is usually good for most though.
12 hours of light is the amount of light needed?
Yup, and you'll want to make sure it stays the same each day, or close to it.
Why is a bin type enclosure ok but not an aquarium?
Most people who use bins for their hedgies drill small holes about halfway down the bin, all the way around, to help with ventilation.
Offer both bowl of water and water bottle to make sure she understand the concept of the bowl?
Yup, that'll work well. Most people who switch from bottle to bowl just put the bowl under the bottle spout and the hedgie usually catches on pretty quickly.
Enrichment toy ideas? what should be stayed away from?
If you look in the toy section, there's lots of threads and ideas! Some main ones are Easter eggs with treats in them, cardboard egg carton cups (treats hidden under), small action figures, small stuffed animals, 4-inch PVC pipes, small cat toys, etc. The main concerns are no strings that can wrap around legs, no holes where jaws, toes, nails can get caught in, and no small pieces where they might bite them off and swallow.
Anyone used Aspen? pros and cons?
Few pros, many cons. Hedgehogs can get mites from wooden bedding and often do. The mites are species-specific, which may be why you haven't had the issues with your gerbils yet. Wooden shavings are also messy, can be sharp, can get stuck in private areas, and you have to keep buying them for as long as you're using them. The preferred bedding on here is by far fleece liners. You can do just about whatever you want for them - one layer, or many. Fleece on top and denim or cotton on bottom, flannel on top instead of fleece, etc. They're clean, easy to change, you can wash and re-use, and you can make your cage look pretty with different fabric patterns. Also no risk of mites or getting stuck anywhere.
Nail trimming ideas?
There's also a lot of threads on this topic, I think mostly in the health forum, or perhaps general questions or behavior. If you use the search feature for "nail" or "nail clipping", you can find topics more easily. One of the popular methods is clip them in the bath, since most hedgies won't ball up in water to avoid water in their face. You'll have to wait and see how she does with nail clipping though...Some hedgies struggle like ****, some don't really care...I got lucky and Lily doesn't care too much. You can also help make it easier by playing with her feet during cuddle time as much as you can, just touching and rubbing them. It'll hopefully get her used to having you touch them more so that she doesn't mind so much when you're trying to clip.
Also, because they walk on the pads of their feet and not on their nails/toes, any kind of sandpaper or grippy paper or anything like that on their wheel is not a good idea. Any rough terrain on their wheel can shred their feet since they run so much in a night. Likewise, having a brick or stone in their cage isn't likely to help much.
Teeth growing continuously?
Nope, they don't, and hedgies don't have the urge to chew, so they don't need wooden chew toys or anything of the like.
First Aid kit items?
Nancy has a list right here as a sticky. viewtopic.php?f=5&t=38
Welcome to the forum and it's great that you're doing so much research beforehand! I highly recommend reading all of the stickies (all of the topics at the top of the list) in all of the forum sections, and reading as many topics as you can. The more reading, the more prepared you'll be...Though I know that won't make a bit of difference when you finally bring her home and are wondering what on earth you got yourself into.