Getting a young corn is a lot of fun. They grow fast and it is really fun to watch. A couple things to note, and then I will answer your housing question.
First, young corns are TINY! They are delicate, fast, and often defensive (although they cannot do any damage and they grow out of it really fast 99.9% of the time). I got Figment (
https://ball-pythons.net/forums/show...nder-Corn-Baby) at 9G and he's 5 now and about 650G and about 5FT. He was flighty, but never defensive. He's still quite active, but very calm comparatively, and he calmed down quick. Solana (
https://ball-pythons.net/forums/show...ow-Motley-Corn), a more recent acquisition, is now 8 months old, and we got her at 2 months old and 8G. She was defensive the first two days and during her first shed a week later and would rattle her tail and fake bite/strike with her mouth closed and hit my hand or Katie's hand. We would call he bluff and pick her right up. Once she realized we weren't going to eat her, she calmed right down. After the fist week, she's been nothing but calm since. She actually is incredibly calm for a corn snake, period. I just want you to be prepared for tiny, tiny, cuteness, nothing like a young BP. This also makes them great escape artists, so be prepared for that too.
Secondly, they grow fast and go through a lot of different food items quickly. You will need frozen mouse small pinkies, normal pinkies, small fuzzies, normal fuzzies, hoppers, weaned mice, and finally, adult mice, through the first two years of having a corn. The pinkies, fuzzies, and hoppers, will all be in the first year.
Okay, here are the answers to your questions, in order, and labeled.
1. You can keep a young corn in just about anything for the first few months. Frankly, if you want to make it easy and keep costs down, I would get a reptile designed 5 or 10 gallon enclosure. Humidity is not a big issue for corns (as you alluded to later in your post) so a screen top is fine. However, I would get a sliding screen top with lock, designed for reptiles, or a front opening tank, but a small one will work great for a while. A 10G will last for a year or so. You can get a small UTH and if your room temp is 72F+ just use that for an 84F hot spot and you are done. I prefer to keep ambient around 78F for my corns, with an 83-84F hot spot, and a 75-76F cool spot, but they are okay with room temp as long as they have an 83-85F (max 85F) hot spot to digest.
Secondly, the idea that (most) snakes need tiny tanks is a fallacy, in my mind, and from most breeder's minds that I've talked to. There are exceptions to this rule, yes, for species, and for individual snakes. However, there are advantages to larger tanks, and there are ways to make snakes feel secure. These are not always easier for the keeper, but they can and do work. Don Soderberg, from South Mountain Reptiles, and Solana's breeder, said it best to me when I asked about moving her from her 10G quarantine tank into her 3X2' life tank at 5 months of age and 20G. He said, "how much space is there in a forest in Florida, or New Jersey, or anywhere in between?" Corn snakes adapt to large environments, by finding small spaces to feel secure. To make a small corn snake, or any snake feel secure in any environment, but especially, a larger one, give them plenty of clutter and/or hiding spaces. For Solana, I have 6 hides and 2 water bowls in her 3X2' (which for reference is a little bigger than a 40G breeder - a little bit deeper). She cannot move more than 4 inches without hitting a hide.
Again, are there exceptions to this rule? Yes, I've heard Hognose snakes do not do well in large enclosures even with many hides, and BP's can struggle. However, in my experience, even with young BP's, in 4X2' tanks, give them plenty of hides, and clutter it up, and they do fine as well. The advantage of a large enclosure is that you can more easily create a temp gradient and generally more reliably create proper temp zones.
The downside of having a small snake in a big tank with many hides is finding him/her.'
In any event, in my experience, and in talking with breeders of corn snakes, BP's, and Boa's (BCC and BCI), proper humidity and temps are more important than a tight space as long as you create an environment that feels safe to them by cluttering it up and giving options to hide in different temp zones.
So, bottom line, get a cheap tank, or a tub size that works for you, get a heating element, UTH, etc. that works for you, and get some hides, and make it work for the new corn snake. Just my opinion, but I think you will be fine.
2. Corn snakes can benefit from a moist hide, but unless it's really dry, I usually just mist 1-2X a day when I know they are going to shed and their eyes clear. They don't need a lot of humidity for a successful shed. Figment has perfect sheds if humidity is 45-50% plus and I spray 1X a day or every other day to keep it 55-60% max. Solana, being scaleless, I try to mist daily when I know she's going to shed, and keep it about 60-65% for her. It's not that she needs more humidity, but I want to make sure she has a good shed. On the off chance Figment's isn't perfect, being scaled and protected by his "armor," a quick soak in some shallow warmish water with a towel over the container to increase humidity and it comes right off. I'd have to be a little more careful and gentle with Solana, so I work a little harder to ensure she has a great shed.
On humidity, corns are fine with, breathing and health wise, etc. with humidity from about 30%, give or take, to about 60-70% give to take. A good sweet spot for them is 45% or so. However, keeping a water bowl in my boaphile tanks, which hold humidity well, and offset the drying effects of the RHP, and then some, means I never spray my corn tanks, even in the dead of winter, unless they are in shed. Only exceptionally low and exceptionally high humidity exposure, for extended periods, will cause issues for corns under normal circumstances (not in shed and with proper temps, etc).
So, just increase the whole enclosure when they are going to shed (after the eyes clear) and you should have a perfect shed every time.
3. I would use printless newspaper for your corn. I use it for all my animals, but I would definitely use it for a corn, or frankly, most colubrids.
First, they have fast metabolisms. Thus, they go the bathroom A LOT! There is also a lot of it and since their metabolisms are fast, it's pretty rank. Figment, after eating a 25G mouse, can clear a room. Behira (BCI) or Shayna (BP) can eat a 115G rat, poop it out 3 weeks later, and it smells like roses compared to what Figment drops 3-4 days after eating. You are going to want to clean that up quickly and well. Trust me. My corns also love to burrow under and in between the paper layers in addition to using their hides.
Secondly, humidity, as discussed, is not a big issue for them, so you do not need a substrate the holds humidity incredibly well.
Finally, see #1 and remember that cleanliness is important with all reptiles and all reptile keeping, but especially with young animals and animals on quarantine/new animals.
I have 12 tanks and 12 animals currently. That means I want easy to maintain and easy to keep clean. That means printless newspaper for me. I don't have time spend an hour a tank changing substrate, disinfecting, etc. Someone goes; paper out, F10SC in, ten minutes later, wipe it up, spray in Healthy Habitat and get everything smelling nice, put new paper in, and done. If I had to fully clean each tank in a day it would take me 2 hours if I had to do each one in succession. Not bad. While the F10SC in disinfecting I am either handling the animal, weighing them, cleaning water bowls and hides, etc. or some combination. Very efficient. Having said all that, I usually break it up and do a couple tanks a day. So it's very manageable.
Anyway, as your collection grows, you may want to consider things like printless newspaper, less pretty tanks/barer tanks that are functional and feel safe for the occupant, but are clean and easy to maintain for you, etc.
I went on here, but I hope this helps.
Feel free to ask for clarification on anything or ask more questions.
Good luck and feel free to post or PM me if you have questions on corn morphs, breeders, etc.