@Piggies&buns Thank you very much for the info on how much hay you use! That's really useful for planning actually, and as I can buy bulk hay very close to me, ~20kg a month should be no problem. I might even use a little less, as I won't be getting a rabbit. I don't know much about rabbits though, nor how much they eat/play with hay in a day, so maybe not too.
@Black piggies Thank you for the multiple replies! They all are full of good information. I'll start with thank you for the compliment, though I'm far too young to be running for President, nor do I think I would want to... ^-^ I prefer having plans in any given day, rather than flying around by the seat of my pants, especially when it comes to things like big, expensive projects and living animals.
I looked them up, and carrot cottages are sold here on Amazon! They look like a great hide, but I probably won't get one until I know for sure my pigs are bonded/if I manage to get an already bonded pair. Although it does look pretty easy to cut them, so maybe... I'm planning on having a big hide right in the middle of the cage, maybe something like a cuddle cube that I can make so that it has two openings, but is big enough for two pigs to snuggle in?
Speaking of temperature though, the basement room can be a bit colder, which I'm concerned about a little. There aren't any windows, it's just underground. The ambient temperature never drops lower the 64-65 F(~17.7-18.3 C), but I figure that if I don't like 65, my piggies won't either. There is also a fireplace, which I believe the piggies will be placed to the side of, but it is never used due to there being a portable space heater that brings the ambient temperature up to about 68-70 F(20-21 C), and the fireplace doesn't connect to the outside. I've looked into those "self warming" pet beds, and at the "how to stay warm" thread, but it didn't seem to apply too awful much to my situation... This is another reason I'm making a stand though, so that they aren't on the floor.
The basement is sort of considered the "Guest Room", and does have a TV, but I can always ask that the volume be soft, or move the piggies temporarily if guests are there. I've heard stories that some pigs will even watch TV with you, which sounds really interesting. As for cooking smells... well, the House is a Ranch style and the only places that have doors are ones that lead to the outside, the Master Bedroom, and the Laundry Room. There will be a good amount of pet-safe deodorizers and scent absorbers near the cage however, as relatives don't want to smell the guinea pigs outside of the basement. I personally don't have qualms about the scent of hay & barn, and find it funny that they don't want to smell my guinea pigs when they have 3 mastiffs and 2 cats, but to each their own. Would these help with smells at all?