You are asking way too many questions for a quick response,
The hole was cut like that, they looked more chinchilla like when I first got them. Someone made them for me, but they looked similar to this
https://exoticanimalsupplies.com/wp...08/chinchilla-cut-out-wood-hay-feeder-box.jpg
I'm in Canada so I'm not sure I can help with where to get it cheaper, I normally buy my hay at either PetSmart or the local feed store. It's kind of interesting on the chinchilla Facebook group I'm in the Small Pets Select is the more recommended, and post picks of nice looking hay, on here people say it sucks,
so I don't know. I've never tried it because the price they charge for it in Canada is horrible. The only dealer of it in Canada is Amazon and it looks like $75 for 10lb box plus shipping.
Yep, they poop about 200+ times a day and they can't control it.
Some people buy and have had no issues and their chins like it, but it comes down to the best hay is whatever your chin will eat, some like the high quality brands others for whatever reason seem to like the lower quality brands like Kaytee. Hay is hay so brand doesn't matter as much like it does for pellets, you can even switch between brands without issue if needed.
Hay makes up about 70-75% of a chin's diet, they should ideally be eating a pile of hay the size of a chinchilla per day.
Not a lot from pet stores is safe unfortunately, or has unsafe parts. Things that look ok are... If they don't list what it's made of I just avoid them. Also you can get things for a lot cheaper from online chinchilla stores then from the pet stores.
Oxbow Timothy Hay Hide & Seek Small Mat
Oxbow Enriched Life Apple Stick hay Feeder
All Living Things® Rainbow Log Chews
All Living Things® Pumice Chew Block (minus the rope, blocks, and glue)
All Living Things® Timothy Hay Bundle Small Pet Treat
All Living Things® All-Natural Timothy Hay Small Pet Rope
Oxbow Timothy Hay Barrel
All Living Things® Small Animal Pumice Ledge
All Living Things® Rainbow Stick Chews
Oxbow Timothy Hay Square
All Living Things® Chilling Stone
That assortment looks good
Those look good too.