Welcome, welcome, welcome! It sounds like you have done your research! Props to you
1) Heating. My setup is a standard wire cage with a plastic bottom. I am using a heat fixture with a heat emitter. My house itself sits at a temperature of about 68-70 and the cage floor has a temperature of about 72-75(I'm going to invest in a digital thermometer. I didn't realize the one I bought only showed me ranges). Is this warm enough? Pear seems to be thriving and she has a shelter with plenty of fleece blankets, but as a new parent I'm just afraid she'll get too cold. I got the lowest wattage bulb because on the box it said the temperature at the cage floor would be between 72 and 76, and the next highest was like 78 and I thought it would be too high. Do you think I made the right choice?
72* may be OK for some hedgies, but hibernation attempts should always be in the back of your mind. The lower in the 70s it is, the more likely your little one is to try hibernating. A lot of people here keep their cage temp between 74* and 77*. Some elderly hogs (3 years old or so) need more like 77-78*, but I think 75* should be your goal temp.
2) How clean do fleece cage liners really stay? Pear had a little bit of loose stool when I brought her home, and this was probably a mixture of stress and I might have given her a little too much of her new food(she seems to pick all the new food out first), and the liners I put in were absolutely ruined. Her tummy troubles have just about cleared up now(I learned to actually count pieces instead of guessing an amount) and I was wondering how useful fleece liners really are? I heard you can litter train a hedgie and I put a litter box in with carefresh but is this realistic? Or will the fleece liners always be poo covered and I'll have to throw them away?
Fleece liners are basically the cheapest, easiest option for bedding. You shouldn't throw away liners - laundering them with a non-scented, hypoallergenic laundry detergent will make them look brand new! How dirty the liners get usually depends on the night. Sometimes, my Mildred keeps her cage neat and clean and I can go a week or a week and half without washing the liner. Other times, I put a new liner in and she has a particularly poopy night on her wheel and it needs to be washed after one day lol.
3) Food choices. I've read over and over the food listings that are recommended for hedgehogs and I chose to buy Innova, Chicken soup for the cat lovers soul, and I'm still debating on a third. Any really good suggestions? I'm still working on introducing the first food, but I would like to figure out the third food ahead of time. Also, I've read about adding baby food? When feeding baby food, do you mix it with the dry food or feed is separately?
Blue Buffalo is a really good brand. I've heard great things about Solid Gold, too. There are lots of threads about this in the diet & nutrition section.
Baby food should be offered in a separate dish from the kibble because of the chance that hedgie will simply refuse the baby food. If all of the kibble is covered in the baby food, there's a good chance hedgie won't eat anything that night. They can be really stubborn sometimes The first time you offer baby food, put it in a dish next to the dish with the kibble in it and only put a little bit (maybe half a spoonful or so) in there so hedgie's tummy can get used to it slowly.
4) How much food do I feed!?! My little girl is only 9 weeks but I feel like she can eat so much! I started with 20 pieces and they were all gone by morning. I don't want to starve her, but I also don't want to overfeed her. How do I know how much is enough? Also when feeding crickets and meal worms, how many of those are okay for her to eat?
All hedgies are different and so is kibble size. Hogs don't normally "binge eat" and most members choose to free feed their quilled friends. When my hedgie Mildred was 9 weeks, she ate about 70 of the CSFTCLS kibbles in one night. That might be a good base number. So put 70 in tonight and see how many are left tomorrow. If there's like 20 kibbles left, try giving 60 kibbles tomorrow. But, if there's no kibbles left, try 80 kibble tomorrow. There should always be at least a few kibbles left in the morning to ensure hedgie is eating it's fill.
I don't have any experience with crickets so I wont' touch on that (all I really know is that they are lower in fat than mealworms are and that some hedgies like to go cricket hunting in the bathtub lol), but how many mealworms really depends on your hog's weight. If she seems to be at a healthy weight (her sides don't look like this ( ) [overweight] or like this ) ( [underweight]), try giving 2 or 3 mealies every other night or so. If you notice weight gain, crickets might be a better option.
Hope this helps.
P.S. We really love hedgie pictures here.